Week 1 (Logistics)

  • Professor Email:
    • tk2436@columbia.edu
  • Professor OH
    • Scheduled via email
  • Course Grading
    • 3 Synchronous Exams
      1. October 07
      2. November 11
      3. TBD
    • 2 Papers
      1. By October 28
      2. By December 14

Week 2

Psychology - the scientific study of brain, mind and behavior

  • brain is the biological aspect of this study
  • mind is the cognitive aspect
    • mental processing, usually cannot be observed
  • behavior is the observable aspect

Short History of Psychology

What constitutes the mind? How do you measure them?

  • 1800’s – early 1900’s:

    • Hermann von Helmholtz was one of the first to collect empirical data associated with the nervous system and behavior. Example of this empirical data was “reaction time”.

      • data that is well controlled and objective
      • reaction time => time between a stimulus to an action
    • Wilhelm Wundt & Edward Titchener believed that scientific study of Psychology should focus on structuralism, or breaking down of elements that constitute the mind; “anatomy of the mind”.

    • William James believed that the scientific study of psychology should focus on functionalism, or how the mind enables people to adapt to their environments. This incorporates understanding behaviors.

      Imagine that in a high school chemistry class, the teacher asks her students for the best way to define water. One student, Mike, says that the way to define water is to break it into its basic components; he defines it as two hydrogen atoms and one oxygen atom. His classmate, Susan, disagrees with him, and says that the best way to define water is to look at its purpose. She describes it as a liquid without taste or color that serves as the main component of lakes, rivers, oceans, and streams, as well as the fluids in most living organisms, including human beings. Mike’s definition is closely aligned with that of structuralism, while Susan’s definition demonstrates the principles of functionalism.

  • Modern

    • well-defined structure in research. See section below.

Modern Scientific Research in Psychology

General Procedure

  1. Decide on a research question/topic
    • that will help determine the scientific prediction to be experimentally tested
  2. Conduct a thorough search in the peer reviewed scientific articles
    • to see what is currently published, thus what is known, or not known, about your research question/topic
  3. Formulate a hypothesis
    • which is formulating an experimentally testable statement of your scientific prediction
  4. Design an experimental methodology to experimentally test the hypothesis you have formulated
  5. Before implementing the designed experimental methodology, obtain institutional approval (ethical purposes)
  6. Once institutional approval is obtained, implement the experimental methodology
    • collect data and consistently
    • analyze the data consistently
    • interpret and write up the data consistently present the data
      • consistently refers to including all the data you obtained, even if it falsifies your theory
  7. Publish the results from the data in a peer reviewed journal!!!


Scientific research in Psychology generally includes the following:

  • independent variable
    • mostly manipulated by the experimenter, and not directly manipulated by other variables within the experimental methodology
    • this needs to be truly independent, changing/related to only one factor at a time in the experiment
  • dependent variable
    • measured by the experimenter, and this can be the outcome due to the independent variable, thus an indirect assessment of the experimenter’s manipulation
  • control group of human participants, or control group of animal subjects
    • the group that is not exposed to the independent variable
  • experimental group of human participants, or experimental group of animal subjects
    • the group that is exposed to the independent variable


Some data could be better represented by Bar Graphs:


Sometimes, scatter plots:



  • Flawed Example



    • it is flawed because the independent variable in this case should be randomized: a bird could be responsive to the first image being an image, not the fact that it is a predator
      • namely, it does not only relate to one “factor” of the experiment
  • Good Example


    • its data are also supporting the hypothesis


      • supportive, if there is the assumption is true being anxious means walking around less. See below section.

Validity of Results

This does not talk about whether if your results are “correct”, but if they are really related to your experiment, as there are potential many factors being changed when you manipulate an independent variable.

  • internal validity – degree to which the relationship being tested is trustworthy and not influenced by other factors or variables (if your independent variable is well controlled)
    • e.g. in the above example, is movement time only affected by the Kpas4?
  • construct validity – degree to which the variables of the experimental methodology measure what they are supposed to measure
    • e.g. in the above example, is movement time in an open field a good measure of anxiety? What if there are disabilities caused by knockout of Kpas4 that also affects movement time => measuring disability? What if it makes them more tired => measuring tiredness?
  • external validity – degree to which the results of the experimental methodology can be generalized to the “real world”
    • e.g. how results of mice can be generalized to human

Experimental Methodologies

Basically, ways of collecting data:

  • case study – experimenter intensively observes, describes, and documents the observations and descriptions of a “unique” participant or participants
    • so participants are aware of being experimented
  • naturalistic observation – experimenter is passively, usually separated from what they are observing, to ensure that they are not altering the environment of what they are observing
    • participants are not aware of being experimented
  • self-reports – experimenter administers surveys or questionnaires, or interviews, to participants
    • those surveys have to be well-designed

However, there are some common caveats in those methodologies:

  • confounding variable(s) – extraneous part(s) of the experimental methodology, usually out of the experimenter’s ability to eliminate/control, that may affect the outcome
  • reactivity – if a human participant knows their behaviors are being observed as part of the experimental methodology, that participant may alter their behaviors
    • the placebo effect
  • experimenter expectancy effect – due to expectations of the experimenter, the experimenters themselves may not be aware that their expectations are altering the experimental methodology to fulfill their own expectations


Before doing the experiments mentioned above, they need to be approved by either:

  • Institutional Review Board (IRB)
    • for human participants
  • Institutional Animal Care and Use Committee (IACUC)
    • for animal participants

In general, for an experiment to be ethical, you need to:

  1. Experimental methodology should be designed to minimize harm/pain/distress (humans, animals) and to ensure more benefit than risk
  2. Informed consent – fully informed of the nature of the research; potential risks and benefits; confidentiality; right to withdrawal at any time
  3. Use of human deception - those who volunteer to be part of an experiment have the right to know what will happen to them during the course of the entire experiment; if justified, humane deception can be used, but experimenter(s) should debrief the participants after experimental participation
    • to help with naturalistic observation
  4. Vulnerable populations should be treated with special care and implementations - ensures thoughtful decisions on behalf of the participants as to whether or not to participate in the proposed scientific research

Anatomy of Nervous System

Suppose you are asked to raise your right hand. What happens to your brain that causes your movements?

  1. your brain processes the request
  2. your brain parse what is needed to respond to it
  3. your brain sends a signal to the muscle of your right hand
  4. right hand raises

In short, your brain/mind/thoughts have altered some area of your blood flow such that you behave what you are behaving.


  • neuroaxis for humans
    • imaginary “line” which spans the “midline” of all the segments of the spinal cord, up and through the “midline” of the brain


  • Ipsilateral
    • denotes anatomical structures located on the same side of the body, with respect to the neuroaxis
      • e.g. left eye is ipsilateral to left ear
  • Contralateral
    • denotes anatomical structures located on the opposite side of the body, with respect to the neuroaxis
  • Lateral
    • denotes anatomical structures located more peripherally, with respect to either the neuroaxis, or, to other anatomical structures within the body
      • e.g fingers are more lateral than eyes
  • Medial
    • denotes anatomical structures located more “in the middle”, or at the midline, with respect to either the neuroaxis, or, to other anatomical structures within the body

Nervous System



  • central nervous system includes
    • your brain
    • your spinal chord
  • peripheral nervous system includes
    • somatic (躯体的) nervous system - associated with the voluntary control of body movements via skeletal muscles
      • cranial nerves
      • spinal nerves
    • autonomic (自主的) nervous system - acts largely unconsciously and regulates bodily functions
      • sympathetic nervous system
      • parasympathetic nervous system

In summary:


In everyday life, all biological cells of our central nervous system (CNS), and, all biological cells of our peripheral nervous system (PNS), work together for the:

  • processing of incoming, afferent (sensory) information; this process originates from the PNS to the CNS
    • e.g., when you hear that you need to raise your right hand
  • processing of outgoing, efferent (motor) information; this process originates from the CNS to the PNS
    • e.g. actually raising your right hand
  • processing of sensorimotor information
    • e.g. combining the above two, happening almost synchronously

Anatomy of CNS and PNS Cells

They all have the same anatomical structures


For example, when you want to raise your right hand:

  1. Your brain changes the blood/current flow around the cell, which changes the electrical potential
  2. Proteins sensitive to changes in voltage would open
  3. Net influx of ions into the cell
  4. Activates this biological cell, and it is the beginning of everything

Difference between CNS and PNS Cells

Even if they have the same structure, they have different names:

  • CNS cells are called neurons
  • PNS cells are called nerves

This is because:

  • neurons are all situated in the brain and the spinal chord


  • nerves always have part of the axon located outside brain/spinal chord



    • we have afferent nerves
      • where cell body is outside the CNS, terminals inside
      • are afferent, since they gets information from the outside
    • we have efferent nerves
      • where cell body is inside the CNS, terminals outside
      • are efferent, since they gets information from the inside CNS
    • there are also cranial nerves and spinal nerves
    • we see that each cell has at least part of the axon (轴突) being outside the CNS
      • probably because it needs the information from and to the CNS to work correctly. e.g it processes afferent information and needs to carry it to the CNS


  • the actual mechanism of how information is transmitted from a nerve to a neuron is:
    1. Usually the begins in the cell body area, where receptors on the dendrites open up
    2. Inflow of ions affect charge density/voltage
    3. Triggers release of chemical at axon terminal, which is usually inside the CNS
    4. Those chemicals bind to the neurons in CNS, and activates the receptors there

Cranial Nerves and Spinal Nerves

Module - Spinal Cord and Spinal Nerve (8 of 14)

Cranial(颅) nerves tend to be located at the level of the brain

  • hence above the spinal nerves

  • for example, related to your nose, eyes, tongues, neck

Spinal nerves tend to be located at the level of spinal chord

  • hence below the cranial nerves

Autonomic Nervous System of PNS

An autonomic nervous system is a system, without conscious direction, regulates important bodily functions such as heart rate, blood pressure, pupil dilation, body temperature, sweating and digestion.

  • basically they control neurons, which control these different physical reactions by directing the action of skeletal muscle, cardiac muscle and gland secretion.

This system allows animals to make quick internal adjustments and react without having to think about it.

The entire system is made of two parts: sympathetic nervous system and parasympathetic nervous system.

And here, we are also reminded of the fact that CNS and PNS work together.

  • sympathetic nervous system is the nervous system that expends body’s stored energy
    • “fight-or-flight” response is driven by the sympathetic nervous system, a normally harmonized network of brain structures.
    • basically where our body internally forces us to either fight or flight
    • “activated” by a stressor
  • parasympathetic nervous system is the nervous system that increases body’s energy
    • basically our body internally forces us to rest and restore
    • “activated” by a stressor being gone

For example

  • Scenario:

    You are walking alone in the midnight of a dark alley, you hear footsteps behind you coming up. You got really nervous. After a few seconds, he walked passed you. You got relieved.

  • Analysis:

    Your body activated the fight or flight response of the sympathetic nervous system due to the stressor of:

    • you receive afferent information of being in a dark surrounding, and hearing footsteps
    • you receive bad/stressful memory from your brain from the CNS of being alone at midnight

    And your body activated sympathetic nervous system:

    • activated cranial nerves of the PNS
      • which makes you become concentrated in sensing surrounding information
    • activated neurons in the brain/spinal chord
    • activated neurons in the spinal chord activate spinal nerves (PNS)
      • those spinal nerves release chemicals to increase activation of biological cells
        • hence heart-beat pumping up and etc

    However, when the man passed by, the stressor is gone. And your body activated parasympathetic nervous system:

    • the same process as above, but in the end spinal nerves release chemicals to decrease activation of biological cells

Brain and Spinal Chord of CNS


Mainly composed of large mass of neurons and glia.

It is a very protected structure within human body.

  • very restricted inflow/outflow of materials between the CNS and the outside part of body, hence protected

It also requires consistent flow of blood and oxygen to extract energy

Glial Cells

They are actually more abundant in the CNS and PNS than neurons/nerves are.

They make crucial contributions to the formation, operation, and adaptation of our neural circuitry.



  • the circled ones are glial cells
Anatomy of Brain



  • the outer layer (top two pictures) are cortex (皮质)
  • the inner structure (bottom two pictures) are subcortical structures
    • for example:
      • amygdala which process emotions such as fears
      • hippocampus which process learning, memory, spatial navigation
        • also the place in brain with the highest density of neurons

Outside your cortex, this is



  • this is how your brain and spinal chord gets protected
  • the layers are meninges are really hard to penetrate


  • Spinal taps are there to penetrate your dura and arachnoid membrane to collect your spinal fluid.
    • which cushions the brain and spinal cord from injury and also serves as a nutrient delivery and waste removal system for the brain.

Back to the gross levels, you can divide the subcortical brain into 4 sections:

![Primary brain regions. Motor cortex is the region in charge of… Download Scientific Diagram](https://www.researchgate.net/publication/331905251/figure/fig2/AS:738574852968452@1553101375714/Primary-brain-regions-Motor-cortex-is-the-region-in-charge-of-planning-control-and.png)


  • temporal lobe
    • process the sense of hearing
  • occipital lobe
    • process vision
  • parietal lobe
    • process taste
  • frontal lobe
    • executive functioning/decision making
    • memory
    • intelligence
    • still under research

Spinal Chord



  • in the cross section of spinal chord:
    • grey matter (dark blue part) are basically your nerve’s cell bodies where communication between neaby cells happens
    • white matter (white part) are your nerve’s axons that travel between brain regions
  • the C/T/L/S are called the Dermatomes:

    • an area of skin that is mainly supplied by a single spinal nerve. There are 8 cervical nerves (note C1 has with no dermatome), 12 thoracic nerves, 5 lumbar nerves and 5 sacral nerves. Each of these spinal nerves relay sensation from a particular region of the skin to the brain.
    • This means you can neither feel it nor control it if that part of the spinal chord is disconnected. See Spinal Chord Injury

Spinal Chord Injury

Spinal Chord Injury includes:

  • contusion

    • just bruises
  • hemisection

    • half of spinal chord is severed
  • transection

    • entire of spinal chord is severed



    • LHS is Transection at the level of the cervical spinal cord results in Tetraplegia(四肢瘫痪)
    • RHS is Transection at the level of the lumbar spinal cord, results in Paraplegia(截瘫)


  • neurons and glial cells are damaged, but neurons do not regenerate
    • and that’s why you have all those hemisection or transection.

Week 3

Anatomy of Neurons

Again, we come back to this picture:


where we have:

  • Membranes


  • Intracellular and extracellular fluid
    • In the intracellular (inside of neuron) fluid and the extracellular (outside of neuron) fluid, there are different concentrations of anions (-) and cations (+)

Giant Squid Experiment - Neurons at Rest

The Nobel Prize in Physiology or Medicine 1963 was awarded jointly to Sir John Carew Eccles, Alan Lloyd Hodgkin and Andrew Fielding Huxley conducted an experiment do to with those neurons using a giant squid


and they took the circled part (axon of neuron) and measured their electric potential in vitro (outside the squid body):


where they found:

  • At rest, or when the neuron is not disturbed, the inside of the neuron (intracellular fluid) is negatively charged (-70 mV) with respect to the outside of the neuron (extracellular fluid).
    • This is known as the neuron’s resting potential. This is in fact the same in human.

Forces Contributing to the Resting Potential

Basically, what caused the (negative) resting potential.

  1. Force of diffusion - when there are no forces or barriers to prevent them from doing so, molecules will diffuse from regions where they are more concentrated to regions where they are less concentrated

  2. Force of electrostatic pressure - cations (+) are “pushed away” from regions with an excess of cations (+), and anions (-) are “pushed away” from regions with an excess of anions (-)



  • boxes (for example the blue box surrounding the $K+$)
    • indicate concentration levels of the ions, so the greater the size of the box, the greater the concentration
  • forces and their directions
    • are indicated by arrows. For example, for the $K+$ ion inside the neuron, force is balanced.
    • for $Na+$ outside the cell and the $K-$ inside the cell, forces are not balanced

And for those two unbalanced force, this is because there is actually another contributing force in the cell:


  1. Sodium Potassium (Na+K+) pump
    • This sodium potassium (Na+K+) pump is embedded in the membrane of the entire neuron
    • While the neuron is at rest, the Na+K+ pump continuously pumps more Na+ out of the neuron while pumping less K+ into the neuron

Giant Squid Experiment - Neuron Action Potentials

Now, suppose we apply some excitation to change the electrical potential of the cell itself.

  • remember, all movements/signals for cells are driven by electrical potentials

Here, the experimenters are administering an positive electrical current to the inside of a resting neuron will produce an increase of this neuron’s electrical potential.



  • now neurons have a higher potential (more positive)
    • An increase in neuronal electrical potential is known as depolarization.
  • obviously it is still in vitro (outside the Squid body)

and this is the resulting graph of potential:



  • stimulus is technically defined as:
    • **any external object or event that elicit a response **
  • action potential
    • only electrical current number 4 achieved trigger/fires it
    • is the voltage of this current resulted in a reversal in the electrical potential of the neuron (from the inside of this neuron being negative in potential to being positive). This reversal is necessary for the depolarization to be labeled an action potential.
    • this is when a neuron sends information down an axon, away from the cell body.
  • repolarization
    • this neuron’s return to its resting potential, (-70 mV), from its current state of depolarization
  • afterhyperpolarization/hyperpolarization
    • a transient undershoot of its resting potential, so that the electrical potential of the intracellular fluid of this neuron is decreased to voltages even less than this neuron’s resting potential

Real Mechanism of Neuron Activation

Now we know that when the voltage inside the cell gets above a certain threshold, all the interesting things (action potential) happen. In real life, this is what action potential do:


  1. When the receptors or channels embedded in the membrane of the dendrites open, there will be an influx of cations (positively charged ions such as Na+) from the neuron’s extracellular fluid going into the neuron’s intracellular fluid
  2. Summation of the electrical potentials from the influx of cations (Na+) occur at the axon hillock
  3. If summation of the electrical potentials from the influx of cations (Na+) at the axon hillock reaches the threshold of excitation for this neuron, an action potential occurs and travels down the axon of this neuron
    • i.e. if the summation of cations increased the electrical potential (depolarization) inside the cell to above the threshold
  4. action potential - the brief electrochemical event of a neuron that travels from the cell body area of the neuron to the axon terminals (terminal buttons) of the same neuron (all or none)
    • this basically acts as sending information to the rest the cells in your body

Graphically, this is what happened in a real cell



  • “afterhyperpolarization aka hyperpolarization” is due to K+ channels not closing immediately, even after the neuron’s resting potential is reached.

Role of Myelin Sheath

Myelin sheath on the axon acts as an electric insulator for the conduction of those electricity.


where, with myelin sheath:

  • reduces the ability of any electrical potential to leak out at the myelinated parts of the axon, thus increases the conduction velocity of the action potential
  • much less influx of Na+ is needed to enter the neuron for these retriggered action potentials 为了延续这个potential (because the neuron is already depolarized). Therefore, less energy is needed for these action potentials to reach the axon terminals

Real Life Application - BMI (Brain Machine Interface)

Now, this means you can record the electric potential pattern in your brain (motor cortex) for any given action, and then program it such that:

  • when that pattern is observed, the robotic arm would do that corresponding action
  • this means you can control robotic arms “remotely” with electrodes planted in your brain detecting for electric potential

For example, a sample image looks like



  • the redline would be the $0$ potential
  • everything to the left hand side of the finger would be the resting potential
  • there is an action potential to the right of the finger, whose spike exceeds the positive $0V$
  • your brain can somehow control /generate electric potentials

Week 4

Anatomy of a Synapse

Synapses are the sites of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector).

Essentially, it refers to an area:


where it is composed of:

  • Axon terminal of the presynaptic neuron
  • Dendrites of a neighboring postsynaptic neuron
  • Extracellular fluid in between

And when the action potential travels down the axon of the presynaptic neuron, neurotransmitters are released to bind to and open the receptors postsynaptic neuron.

  • and it is with those endogenous neurotransmitters that we continued or neurotic signal


Some roles/properties of a neurotransmitter:

  1. must be synthesized/produced within the neuron
  2. have the capability to be released from the presynaptic neuron when an action potential occurs
  3. activate channels, and/or specific receptors, both of which are embedded in the membranes of dendrites of the postsynaptic neuron.
    • it the end, it will result in the depolarization, and/or an action potential, of this postsynaptic neuron

Ask a Question:

  • How does the brain provide electric potential that is higher than the threshold so that the first neuron will get triggered?

Types of Neurotransmitters

These are the main types of neurotransmitters you need to know.

  • Glutamate neurotransmitter
    • released from this presynaptic neuron, and will activate channels and receptors of the postsynaptic neuron that allow the influx of only cations (positive) into this postsynaptic neuron
  • GABA (Gamma-aminobutyric acid) neurotransmitter
    • released from this presynaptic neuron, and will activate channels and receptors of the postsynaptic neuron that allow the influx of only anions (negative) into this postsynaptic neuron
  • Serotonin/Dopamine/Norepinephrine/Acetylcholine neurotransmitters
    • released from this presynaptic neuron, and will activate channels and receptors of the postsynaptic neuron that allow the influx of cations, and/or anions, into this postsynaptic neuron


Consciousness are the states of awareness of one’s cognitions, and one’s environment.

  • we can experience and exhibit various states of consciousness (e.g. high state of consciousness during exams, low state during sleep)

Circadian Rhythm

All of our states of consciousness can occur within our circadian rhythm

  • Circadian rhythms are 24-hour cycles that are part of the body’s internal clock, running in the background to carry out essential functions and processes. One of the most important and well-known circadian rhythms is the sleep-wake cycle.

  • Different systems of the body follow circadian rhythms that are synchronized with a master clock in the brain. This master clock is directly influenced by environmental cues, especially light, which is why circadian rhythms are tied to the cycle of day and night.

Extension: Onset and Offset of Sleep

The parts of the brain that is responsible to sleep are the follows:


The onset and offset of sleep is a culmination of many different events:

  • retinohypothalamic pathway
    • retina/your eyes sends information to the suprachiasmatic nuclei of your hypothalamus regarding the amount of light in the external environment (via the suppression/activation of a hormone, melatonin, done by pineal gland
    • the suprachiasmatic nuclei use this information to coordinate circadian rhythms with the solar day
  • circadian “oscillators”
    • networks of biochemical feedback loops that generate 24-hour rhythms in organisms from bacteria to animals. The oscillator cycles with a stable phase and is synchronized with solar time.
  • differences in large scale/overall field electrical potentials of the brain
  • dreams
    • a phenomenon that combines different states of consciousness during sleep, if verbally recalled during wakefulness, this verbal recall can be considered a behavioral event

Extension: Sleep Experiments

Sleep experiments are usually conducted within sleep labs, which contains:

  • Bedroom (or bedrooms) adjacent to an observation room
  • Experimenter prepares the subject for measurements
    • Electroencephalogram (EEG)
    • Electromyogram (EMG)
    • Electro-oculogram (EOG)
    • Other transducing devices

All the above allows us to assess physiological events associated with sleep

Electroencephalogram (EEG)

Electroencephalogram (EEG) is a non-invasive biological procedure that places multiple electrodes along one’s scalp to measure and record the large scale field electrical potentials of the brain (EEG recordings are not recordings of strictly action potentials)

  • large scale field electrical potential $\neq$ action potentials, as they are non-invasive, they are just detecting the overall voltage of parts of your brain, therefore including action potential + potential from extracellular fluid.


Brain/EEG Waves

Brain waves basically refer to the waves you see in an EEG, which comes from oscillations of your large scale electric potential.

In general, we have five types/rhythms of brain waves:

  • Delta
    • slowest brain waves associated with deep/dreamless sleep
  • Theta
    • slightly faster waves, associated with being in a drowsy state
  • Alpha
    • arising in the occipital lobe (associated with vision processing), being wakeful rest
    • comparatively more aware of oneself, rather than surrounding
  • Beta
    • normal wakeful consciousness
  • Gamma
    • normal visual consciousness
    • high cognition



  • all of the above occurs in our circadian rhythm. This means that they can occur during the day and/or during our sleep

Brain Waves Cycle During Sleeping



  • alpha is not in the normal cycle of sleep, but the rest is
  • deep sleep is often referred to as SWS (slow wave sleep)
    • SWS is thought to be important for memory consolidation
    • dream can also occur during SWS as well
  • REM sleep is usually the most useful dreams
    • associated with benefiting learning and memory
REM Sleeping
  • Rapid eye movements
    • as compared to no rapid eye movements during SWS
  • Increased cortical activation
    • as compared with less cortical activation during SWS
    • basically activated parts of your brain
  • Lucid dreaming (see definition below)
    • as compared with non-lucid dreaming during SWS
    • high awareness of one’s own cognition while one is in the sleep cycle
  • Skeletal muscle paralysis (a form of atonia)
    • as compared to none during SWS
    • basically muscle has lost its strength
    • therefore, you cannot easily act out of your dreams

Lucid Dream:

  • There are in fact two states of lucid dream:
    1. primary state of consciousness associated with lucid dreaming – high awareness of one’s own cognition while one is undergoing the lucid dream
    2. secondary state of consciousness associated with lucid dreaming – high awareness of one’s own cognition that one is in fact dreaming, while one is undergoing the lucid dream
      • experimentally, it is found that this only occurs during gamma waves

Notice, the above definition means that:

  • promoting gamma brain activity during REM sleep may help to restore dysfunctional neural network connectivity, so that you can more easily distinguish reality vs non-reality even if you are awake


Another state of consciousness that is altered/not natural (hence unlike the circadian rhythm)

However, the exact definition of a drug is amorphous. Because it could also depend on the intention of the one taking it, and etc.

Here, we are just focusing on those drugs and their effects in changing our circadian rhythm/normal behavior.

Effectiveness of Drug

  • Affinity of a drug
    • how firm/plausible molecules of a drug binds to the receptors of our neurons/nerves
  • Tolerance/Repeated Administration
    • as its name suggest, would you be less responsive of a drug once you have taken it, hence over time needing larger doses?
  • Response Curves
    • the relationship(s) between administering doses of the drug, and the effectiveness, or lethality, of those administered doses
Binding Affinity

Ligand (biochemistry) - Wikipedia

  • A drug with a high binding affinity will have properties that increase the probability of the drug molecule to activate its intended target (eg., receptor), even if this drug is administered at low doses
  • A drug with a low binding affinity will have properties that, when compared to a drug with a higher binding affinity, will have lesser of a probability to activate its intended target (eg., receptor), even if this drug is administered at high doses
  • Effects of tolerance
    • After repeated administrations of a drug, a person becomes less responsive to the drug, and/or more administration of the drug is needed for the effects of the drug


  • The above is achieved by, for the CNS, neurons may have produced second messengers (molecules that will trigger intracellular signaling mechanisms) to categorize them as “memory” neurons.
  • Effects of cross tolerance
    • After repeated administrations of a drug, if a person has developed tolerance to a particular drug, then this tolerance often generalizes to other drugs that are within the same chemical class as the drug that the person has developed tolerance to
  • Effects of sensitization
    • opposite of tolerance
    • After repeated administrations of a drug, a person becomes more responsive to the drug, and/or lesser administration of the drug is needed for the effects of the drug
Response Curves

Basically quantitative representation of the above:



  • $ED_{50}$ shows how much dose needed to give 50% of maximal effectiveness
  • in the above example, Drug A is more effective

There is also a version plotting the lethality:


  • $LD_{50}$ shows how much does needed to have the $50\%$ probability of death
  • The wider the therapeutic index, the safer.
    • as this means you are further away from lethality

Agonist vs Antagonist

  • Drugs that act as agonists will “facilitate” postsynaptic effects
  • Drugs that act as antagonists will “not facilitate” postsynaptic effects
    • notice that facilitating the postsynaptic effects can happen both in presynaptic neuron and postsynaptic neuron

For example:


  • agonists drugs can serve as a “precursor” for the synthesis of a neurotransmitter in the presynaptic neuron, therefore, increasing the molecules of this neurotransmitter so that these molecules can be released into the synaptic cleft
    • for example, dopamine
  • antagonist drugs inactivate an enzyme (protein) for the synthesis of a neurotransmitter in the presynaptic neuron, therefore, decreasing the molecules of this neurotransmitter so that these molecules cannot be released into the synaptic cleft
    • for example, serotonin
  • agonist drugs that binds to a neurotransmitter’s receptors on the presynaptic neuron to block this receptor, so that this neurotransmitter will not be “re-uptaken” back ; therefore, more molecules of this neurotransmitter will be released into the synaptic cleft to allow greater influx of cations, and/or influx of anions, into its postsynaptic neuron
    • this is the tricky one
    • for example, cocaine
  • antagonist drugs binds to receptors on the postsynaptic neuron to not allow the influx of cations, and/or influx of anions, into this postsynaptic neuron
    • for example, opioid

Week 5 (Midterm 1)

Sensation vs Perception

  • Sensation: cognitive ability to detect environmental stimuli (what we see, hear, taste, smell, or touch), so that this detection activates our sensory system(s)
    • this is empirical
  • Perception: cognitions during which we integrate, organize and interpret incoming sensory information that is useful and meaningful for us
    • this is subjective
    • this is the part that results in conscious experience of the world


An example would be:



  • Interpreting as “THE CAT” happens because your perception comes after your brain processes the sensory signal, which picks on the interpretation makes sense in the context

Yet, for humans, we often don’t have an infinite capacity to detect all intensities of environmental stimuli

  • we cannot detect all environmental stimuli, and those thresholds are also defined by measures such as “Just Noticeable Difference (JND)”, “Absolute Threshold”, “Sensory Adaptation”. See the section on Psychophysics.

Mechanism of Sensation and Perception

  • Conversion of environmental stimuli into “biological, neural” signals for the successful detection of these environmental stimuli; this is known as sensory transduction
    • Sensory transduction, for all our senses, begins with the activation of first order neurons associated with processing each of the human senses
  • Our experience of the world (what we see, hear, taste, smell, or touch) results from brain processes that actively construct perceptual experiences from sensory information.


  • To strengthen what we knew: the processing of all of our senses begin by converting “non-biological”, or environmental stimuli, into biological, neural signals

Anatomy of Human Sensory Systems



  • These are the primary brain regions where information about vision, hearing, taste, smell, and touch are projected.
  • Visual information travels in separate “streams” - what you see and where it is - from the occipital lobe (visual cortex) to different parts of the brain for further processing.

Brain in Perceptions

What you experience/perceive are all illusions constructed by your brain.

Despite the fact that the objects and events you are experiencing exist in the space around you, your experience is a construction of your brain and resides inside your skull. Neurons inside your brain do not directly experience the outside world. Instead, they communicate with other neurons inside and outside your brain. Neurons talk to neurons in total darkness.

Therefore, what you perceive, then, is vastly different from the pattern of stimulation your eyes are taking in (for example). In fact, most of the computations the brain performs never reach your consciousness. Only important new outcomes do.


Psychophysics are procedures that measure the intensity of an environmental stimulus, and a person’s ability to detect this intensity

  • in fact, one of the goals of psychophysics is to determine how much (threshold) of the environmental stimulus is required to evoke (or bring forth) a sensory signal that is biologically processed by humans

For example, those intensities could be measures of:

  • Just Noticeable Difference (JND)
  • Absolute Threshold
  • Sensory Adaptation

Just Noticeable Difference (JND)

JND – when comparing different intensities of an environmental stimulus, the JND is the minimal change in intensity of this environmental stimulus that is needed for detecting this different intensity

\[\frac{\Delta I}{I} \equiv k\]


  • $I$ is the intensity of the original environmental stimulus
  • $\Delta I$ is the difference in intensity between the comparison environmental stimulus and the original environmental stimulus
  • $k$ remains constant, despite variations in $I$
    • e.g. for sound, it is usually $k=0.1$
  • if the difference in intensity is equal or larger than the minimum intensity $\Delta I$, then this is the difference threshold, or the JND, for this particular change in stimulus to be detected

Absolute Threshold

Absolute Threshold - the “minimum” intensity of the environmental stimulus needed for sensory transduction to occur (activation of first order neurons in senses).

Experimenters have derived the absolute threshold from participants’ reporting of their ability to correctly detect the presence of an environmental stimulus 50% of the time this environmental stimulus was presented

For example:



  • remember that threshold is dependent on $50\%$ chances of successful detection

  • this could obviously vary between people

    • e.g. for autisms with huge sensory overload, their absolute threshold would be much lower than ours.

Midterm 2 Material Starts from Here

Sensory Adaptation

Sensory adaptation is when there is a sustained presentation of an environmental stimulus at high intensity, yet the neural activity of the sense associated with this sustained presentation decreases with time

Mechanism of Sensory Adaptation

First, we need to understand how neurotransmitters are released into the synaptic cleft:



  • Vesicles contain molecules of neurotransmitters, and are located in this presynaptic neuron

  • When an action potential is going down the axon of a presynaptic neuron, $Ca^{2+}$ channels embedded in the membrane of the axon terminals open to allow an influx of $Ca^{2+}$ from the extracellular fluid (synaptic cleft), into the intracellular fluid of this presynaptic neuron

  • This influx of $Ca^{2+}$ into this presynaptic neuron will help its vesicles to dock and fuse with the membrane of its axon terminal, therefore, releasing the contents of its neurotransmitter molecules into the synaptic cleft to activate the postsynaptic neuron

Now, sensory adaptation happens because:

  • sensory adaptation is the sustained rapid firing of action potentials due to the presentation of the sustained environmental stimulus
  • This leads to the presynaptic neuron’s inability to influx any more $Ca^{2+}$ because action potentials are firing too rapidly

  • Therefore, no more $Ca^{2+}$ can enter this presynaptic neuron, so that the vesicles of this presynaptic neuron cannot dock and fuse with the membrane of its axon terminal, therefore, there will be no release of the vesicle’s neurotransmitter molecules into the extracellular fluid (synaptic cleft)


  • Basically, lacking $Ca^{2+}$ in the blood concentration will cause difficulties for vesicles to release those neurotransmitters. But also notice that lacking $Ca^{2+}$ has nothing to do with being able to fire action potential or not.
  • Why does this not work with vision? Why, when we fixate our eyes on some images, those images don’t get adapted and disappear?
    • due to the presence of saccade and micro saccade of eyes movement
    • A saccade is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction. A micro saccade is basically a miniature version of the saccade movement.
      • as a result, you never truly fixate at something when you look at them

Week 6

Reading: Chapter 6

  • exam for midterm 2 also start with Chapter 6

Sensation (continued)

Senses Processed by Humans

Basically, some technical terms you need to know

  • Vision
  • Auditory or audition (hearing)
  • Cutaneous (pressure, vibration, pain, temperature)
  • Olfactory or olfaction (smell)
  • Gustatory or gustation (taste)

First Order Neurons

Remember, nerves (whether cranial or spinal) that carry sensory (afferent) information from the periphery have their cell bodies located outside the CNS.



  • Clusters of cell body areas of all cranial nerves, and of all spinal nerves, for the relaying of sensory information are collectively known as ganglion

  • ganglion are known as the “first order neurons” for the processing of the senses

    • they are different from normal nerves, as they have specialized receptors, so that they can be activated by the external stimuli

Example: Cutaneous Sensory Transduction

Sensory transduction for the cutaneous senses of peripheral structures below the head:



  • cutaneous senses - pressure, vibration, pain, temperature - activated those special receptors

  • The dorsal root ganglion are the first order neurons for processing the cutaneous senses of peripheral structures below the head

Then, when the information goes up to your primary somatosensory cortices in your brain:



  • primary somatosensory cortices located in the left and right parietal lobes of the cerebral cortex, are arranged in a somatotopic map to process the cutaneous senses
    • e.g. cutaneous senses on your legs correspond to a certain area on that map
  • blue represents the map for somatosensory cortex (S1)
  • brown represents the map for motor cortex (M1)

Example: Vision Sensory Transduction

As you may have known, the retina part of your eyes are for processing and detecting vision:



  1. Photoreceptive layer in the back of the retina contains rod cells and cone cells. These cells have specialized receptors (opsins) that, when “absorb” photons of light, they become activated
  2. The photoreceptive layer then activates the cells of the middle layer of the retina

  3. The middle layer of the retina then activates the retinal ganglion, therefore, retinal ganglion are the first order neurons for processing the sense of vision
    • they for, it is tricky that the information processing to brain actually is done in a “reverse” physical order


  • Human retina houses ~ 6 million cone cells in the fovea (also part of the retina), which are responsible for processing daytime, color and high visual acuity (clearness/accuracy of vision)
  • Human retina houses ~120 million rod cells in the periphery of the fovea, which are responsible for processing dark adapted vision


  • Triggering the cone works as follows:



    • we only have 3 types of cone cells: S, M, L that allow us to perceive colors
    • and color perceived depends on the combination of the activation of those three cones

Example: Audition Sensory Transduction

The basic detection mechanism is the eardrum:


and the actual mechanism is as follows:



  1. Sound waves from air particles
  2. funneled via pinna
  3. go through your ear canal
  4. vibration of tympanic membrane/eardrum
  5. vibration of malleus transmits vibrations to incus and stapes
  6. which then transmits vibrations to cochlea
  7. finally, reached spiral ganglion, which are the first order neurons for the processing of audition.
Spiral Ganglion

Basically, this is the structure of a spiral ganglion:


and this would be how it is within the cochlea.

The organization of SGN innervation in the mature cochlea. a, In a... |  Download Scientific Diagram

But more importantly, spiral ganglion also have a map for frequency:



  • high frequency detection part is closer to your outer ear (see the top picture in this section). Therefore, as you age, your ability to detect high frequency noise will deteriorate.
Different Types of Deafness
  • Conduction deafness – structures such as the tympanic membrane, or ossicles, are not functioning optimally (remediated using external hearing aid)

  • Sensorineural deafness – cochlea (inner ear) is not functioning optimally (remediated by placing hearing aid in your cochlea)

  • Central deafness – auditory pathway (hence the term “central”) in the brain is not functioning optimally

Example: Gustation Sensory Transduction

Basically, now we have chemicals activating your ganglions:





  • Taste receptors are the specialized receptors that innervate the geniculate ganglion located in the facial canal of the head, which is outside of the brain, but synapses onto neurons in the brain (medulla).

And the experimentally verified tastes you can detect are:


  1. Bitterness
  2. Sourness
  3. Sweetness
  4. Saltiness
  5. Umami (Savory/鲜味)


After sensory transduction, higher order neurons are then associated with neural circuits responsible for our perceptions (which integrates meaningful sensory information)

  • whereas the first order neurons helped

Here, our memories, experiences, emotions and expectations all contribute to our perceptions.

Neurons Contributing to Perceptions

  • receptive fields
  • balance of excitation and inhibition
  • mirror neurons

Receptive Fields of Neurons

Receptive fields of neurons are area(s) on a body surface, (eg., skin, tongue), or area(s) in space, (eg., visual field, auditory field), in which stimulus applied to those area(s) will elicit a response from a neuron

  • i.e. it provides a description of the location at which a sensory stimulus must be presented in order to elicit a response from a sensory cell

  • this also means that, the more receptive a neuron is to that area, the stronger the response will be

Example: Measuring the Neuron’s Response in a Receptive Field

Here, we are measuring how a neuron respond to stimulus in a visual receptive field. Visual field is the area in space one sees without movement of one’s eyes or head (complies with previous definition).


and by measuring the response of a certain neuron, we see



  • the $V1$ neuron that gets measured responded the most to the vertical bar, which also means that the receptive field of that neuron could be that vertical bar exactly.
    • Therefore, other slanted bars will receive a lower response due to lower area lying in the receptive field of that $V1$ neuron.
Principle/Surround Receptive Fields

Principal receptive field of a neuron:

  • a neuron’s most preferred area(s) on a body surface, or in space, as indicated by the neuron’s most increased responsiveness, when compared with this neuron’s less responsiveness to activation(s) of other area(s)
    • so placing the vertical bar in the principle receptive field of a neuron will elicit a larger response than placing it on a surround receptive neuron

Surround receptive field of a neuron:

  • a neuron’s less preferred area(s) on a body surface, or in space, as indicated by the neuron’s decreased responsiveness when compared with the neuron’s principal receptive field

Experimentally, we tend to map the receptive fields of neurons in the brain by presenting stimuli that are sensory modality specific, however, one neuron can have many principal, and many surround, receptive fields, to not just one modality, but also to different modalities

Excitation and Inhibition

Basically, this is about how higher order neurons filters out incoming excitations passed in by first order neurons.

  • Inhibitory inputs, along with excitatory inputs, to neurons, are working together all the time so that incoming sensory information doesn’t overload us. This is also called the balance of excitation and inhibition a neuron receives

  • This balance of excitation and inhibition allows for proper sensory gating, or proper ability to filter out “irrelevant” incoming sensory stimuli for perceptions

A brief mechanism for excitation and inhibition is as follows:



  • first notice that our cortex also have several layers, and in fact, the layer IV (4) is the layer that have neurons processes our sense
  1. Presynaptic neurons relay information to our thalamus
  2. Postsynaptic neurons in our thalamus release GABA or Glutamate (or other neurotransmitters) that either inhibit the (action potential of) neurons in Layer IV, or (if produced Glutamate) to excite them.
  3. Cortical layer IV receive both excitatory inputs, and inhibitory inputs, and now starts to process our senses

In fact, one common example of the above mechanism would be:

  • Feedforward (bottom up) inhibition is whereby a presynaptic neuron (such as a first order neuron for processing one of the senses) activates a postsynaptic neuron, such as a neuron in the thalamus; this postsynaptic neuron, when activated, will release molecules of the neurotransmitter GABA, the release of these molecules of GABA will help balance the inhibition/excitation of the next activated postsynaptic neuron (such as a neuron in cortical layer IV).

This feedforward (bottom up) inhibition is happening all the time in our brains. Neurons of the thalamus allow us to “gate” incoming sensory information so that this sensory information doesn’t overload us.

Example: Phantom Limb

This is the phenomenon where people with amputated limbs are still able to “feel” its existence.

Experimentally, this has to do with feedforward inhibition:


  1. amputation of the first order neurons associated with the amputation of that limb

  2. therefore, a group of postsynaptic neurons in the thalamus for these first order neurons are not activated
  3. experiments have indicated that this group of postsynaptic neurons in the thalamus that are not activated are those that release GABA
  4. the lack of GABAergic inputs to the next postsynaptic neurons in cortical layer IV leads to increased excitation of the neurons specific for processing the cutaneous senses of the amputated limb in this cortical layer, hence the perception that the amputated limb is still intact
Example: Visual Afterimage

This is the phenomenon where if you fixate your vision in the white dot of the first image for some time (e.g. 3 seconds), then by looking at the dot on the right, you will see an American flag

Again, it is the same feedforward inhibition:


This is because:

  • While fixating at a particular color, neurons for this particular color will “inhibit” release of GABA.
  • This inhibition of GABA allows for the transient increase in the excitatory inputs to other neurons associated with another color, to give the transient perception of the visual afterimage.
  • Now, when you switch back to the white image, the transient excitatory inputs of other colors will be more dominant.

This means that, in general, our sense are by default very sensitive, and it is with GABA neurotransmitters that we have controlled our brain to operate on a normal level of sense.

Mirror Neurons

A mirror neuron is a neuron that fires/gets activated both when an animal/human acts (including emotions) and when the animal/human observes the same action (including emotions) performed by another.

  • this means that for that action (including emotion), seeing and doing were the same!

  • not all neurons/actions have this property
  • as you imaged, this is related to learning by imitation and the ability to empathize with others

For example, using the example of monkey grabbing a peanut (action):

  • image-20201020021504969
  • image-20201020021616491

Using the example of facial emotion (emotion):

  • actually doing a happy face
  • looking at the happy face

Triggers a similar neuron response as well, by demonstrating extremely similar temporal and spatial properties.

Location of Mirror Neurons

This part is an extension.


  • According to Professor Kao, those are the locations for the mirror neurons:



    • most of the motor/movement associated neurons are located within the cortex
    • most of the emotional associated neurons are located in the subcortical area, hence increases difficulty of measurement (e.g. time lags)

Gestalt Perceptions

Gestalt perception: understand psychological phenomena by viewing them as organized and structured wholes rather than the sum of their constituent parts.

  • e.g. understand cars are cars, but not as its individual parts such as some iron frames

As a result, some common phenomenon related are:

  • gestalt principle of proximity
  • gestalt principle of continuity
  • gestalt principle of closure

which implicitly means that brains/neurons are more preferred to visual clues that are proximate, and/or continuous, and/or closed.

Gestalt Principle of Proximity



  • Objects that are located close together tend to be perceived as more whole, thus are cognitively grouped together

Gestalt Principle of Continuity



  • Points that form continuous lines are perceived to belong together

Gestalt Principle of Closure



  • Incomplete, “broken” images are perceived as complete, “unbroken” images when they are “closed

Week 7

Perceptions (continued)

Attention in Perception

Forms of attention which modulate perceptions:

  • selective attention
    • requires the observer to focus on a particular object or event, while filtering out irrelevant distractor information occurring simultaneously
    • e.g. unconsciously filtering out the clinking of plates and forks, and many other sounds, while you are listening to the person you are talking to
  • change blindness
    • a failure to notice when a change is introduced to an environment when that change does not affect the meaning of the scene/environment
    • e.g. observers often fail to notice major differences introduced into an image while it flickers off and on again as long as the major meaning of the image did not change


(Reading: Chapter 6)

Learning can be generally defined as the acquisition of cognitive and behavior information.

In general, there are four types of learning:

  • non-associative learning: Responding after repeated exposure to a single stimulus, or event
    • habituation: A decrease in behavioral response after repeated exposure to a stimulus.
    • for example: if you moved to a new house, the rumble of passing trains might disturb your sleep. After you live in the house for a while, you quit waking up to the sound of trains. This action, non-associative learning, is a learnt response to something in the environment. The change in response to the stimulus is a form of learning.
    • sensitization: When our behavioral response to a stimulus increases
  • associative learning: Linking two stimuli, or events, that occur together.
    • conditioning
    • basically, understanding how stimuli, or events, are related.
  • observational learning: Acquiring or changing a behavior after exposure to another individual performing that behavior.
    • For example, you might learn the steps to a new type of dance by watching a YouTube video. By watching others in person or in the media, people may learn what to appreciate or what to fear.

Non-associative Learning

In general, there are two types:

  • habituation
    • a decrease in behavioral response after repeated exposure to a stimulus.
    • We tend to notice new things around us. If something is neither rewarding nor harmful, habituation leads us to ignore it.
    • In general, repeated (but not forever) habituation trials can lead to a state of habituation that lasts several weeks.
  • dishabituation
    • increase in a response because of a change in something familiar is dishabituation
    • For instance, birds might stop singing when they detect a predator, such as a hawk. The absence of bird song (which is usually present) alerts other animals, such as squirrels, to potential danger.
  • sensitization
    • an increase in behavioral response after exposure to a stimulus.
    • the stimuli that most often lead to sensitization are those that are threatening or painful.
      • In general, sensitization leads to heightened responsiveness to other stimuli as well.
      • For example, giving a strong electric shock to an aplysia’s tail leads to sensitization. Following the shock, a mild touch anywhere on the body will cause the aplysia to withdraw its gills.


Mechanism of Non-associative Learning

In simple terms, it is the alterations in the functioning of the synapse lead to habituation and sensitization. For both types of simple learning, presynaptic neurons alter their neurotransmitter release.

  • A reduction in neurotransmitter release leads to habituation.
  • An increase in neurotransmitter release leads to sensitization

Associative Learning - Conditioning

This is how we learn predictive associations, instead of those passive associations in habituation and sensitization.

  • For example, when you are thirty and lost in the forest, you listen for the sound of running water for finding water sources. Hence there is a predictive associations, such as between the sound of water and being able to find the water.

In general, this predictive association is learnt by conditioning

  • Conditioning:
    • the process of learning associations between a stimulus, and some type of response to that stimulus
    • e.g. PTSD. Associate a scene (stimulus) to the feeling of horror (response).
    • Within conditioning, there are two branches/types:
      • Classical Conditioning
        • two stimuli are linked together to produce a new learned response, which is usually involuntary
          • e.g. whenever you come home wearing a baseball cap, you take your child to the park to play. So, whenever your child sees you come home with a baseball cap, he is excited (learned response) because he has associated your baseball cap with a trip to the park.
      • Operant Conditioning
        • a method of learning that occurs through rewards and punishments for behavior, which is voluntary (hence you can voluntary stop it as well)


Classical Conditioning


The above is a picture of the famous experiment, where a dog established a response (salivation) when hearing the researcher’s bell ring (stimulus), as usually the researcher feeds the dog (stimulus).

  • this is a great example because salivation is an autonomous response, that is involuntary for the dog

In general, you to train/pair two stimulus,

  • unconditional stimulus (UCS)
    • one that unconditionally, naturally, and automatically triggers a response. (response takes place without any prior learning)
    • e.g. food
  • unconditional response (UCR)
    • unlearned response that occurs naturally in reaction to the unconditioned stimulus.
    • e.g. salivation due to food
  • neutral stimulus (NS)
    • stimulus which initially (before conditioning) produces no specific response other than focusing attention
    • e.g. bell ringing before paired with food
  • conditional stimulus (CS)
    • substitute stimulus that triggers the same response in an organism as an unconditioned stimulus.
    • e.g. bell ringing after paired with food
  • conditioned response (CR)
    • an automatic response established by training to an ordinarily neutral stimulus.
    • e.g. salivation due to bell ringing
    • this could even include responses each as fear, which will be talked about in the section Phobia and Addictions

Acquisition Phase during Classical Conditioning

  • During Acquisition Phase: initial period of improvement. It covers that period of time from when the learner is unable to respond correctly without assistance through to when they are able to respond correctly without assistance.
    • effects affecting this stage could be:
      • frequency of neutral and unconditioned stimulus presented
      • timing between the neutral and unconditioned stimulus
  • After Acquisition Phase: the conditional stimulus could elicit the conditioned response
    • however, often some other phenomenon happen as well:
      • conditioned stimulus generalization, where a new neutral response, similar to the previous one, could also elicit the conditioned response.
        • e.g. a bell ringing at a different tone also produces the conditioned response
      • conditioned stimulus discrimination, animals learn to differentiate between two similar stimuli if one is consistently associated with the unconditioned stimulus and the other is not.
        • e.g. Pavlov and his students demonstrated that dogs can learn to make very fine distinctions between similar stimuli. For example, dogs can learn to detect subtle differences in tones of different frequencies
      • this is an important ability for us to detect poisonous plants
      • higher order conditioning, is the phenomenon by which a neutral stimulus precedes and is paired with a conditioned stimulus (which already gives a conditioned response). What ends up happening is that the neutral stimulus now becomes a second, usually weaker, conditioned stimulus.
        • e.g. a dog having been conditioned to salivate (CR) to the sound of a bell CS (assuming the bell became a CS by being paired with food). If you then pair a light (NS) with the bell (CS), then the light will become a CS and the dog will salivate (CR) at the sight of the light.
  • Maintenance of CR: after successful acquisition, the conditioned response is continued when the conditioned stimulus (CS) is repeatedly presented/maintained with the unconditioned stimulus
    • e.g. continuing presenting food after the bell ring
Timing Between NS and UCS

Usually, when you do experiments mentioned above, you will record timing between UCS and NS:

  • since you present the UCS after NS, time of UCS $>$ NS.



  • the x-axis can be simply understood as number of milliseconds after presentation of NS at which UCS is presented
  • this basically says, that the ideal time interval for getting a response after acquisition would be about 300ms.
    • obviously, if you presented the UCS too fast, the response might not even have time to appear

The Role of Dopamine

At this point, the key principle of associative learning is expectation and prediction. If a CS has been conditioned so that the organism expects/predicts the UCS (e.g. food) after the CS (e.g. bell), then conditioning is successful.

In effect, what happens in the brain during the above process:

  • the dopamine activity in your brain changes according to the stimulus (i.e. like an autonomic response)
    • dopamine is involved in “addictive” behavior, especially in terms of increased wanting for the addictive substance.
  • the below is data from an experiment testing with monkeys



  • (a) before conditioning, the monkey were happy/surprised (rise in dopamine activity) at the presentation of juice
  • (b) after conditioning, the monkeys were happy at the presentation of light, but none at juice
    • because the monkey has expected/predicted the juice when they see the light, so the UCS was treated not as a “stimulus” in the brain anymore
  • (c) once the UCS no longer appeared after the CS, negative prediction error resulted in decreased dopamine activity.

As the above talked about prediction errors, here are the definitions:

  • Positive Prediction Error - after a stimulus appears, something better than expected (e.g. a reward) happens.
    • A positive prediction error strengthens the association between the CS and the US.
  • Negative Prediction Error - after a stimulus appears, the expected (e.g. reward) did not happen.
    • A negative prediction error weakens the association between the CS and the US.
    • also means how you can “unlearn” the conditioning

Phobia and Addictions

  • A phobia is an acquired fear that is out of proportion to the real threat of an object or of a situation
    • According to classical-conditioning theory, phobias develop through the generalization of a fear experience
    • e.g. when a person stung by a wasp develops a fear of all flying insects.
    • e.g. for the experiment with little Albert: pairing of the CS (rat) and US (smashing sound) led to the rat’s producing a fear response (CR) on its own
      • the key difference later on is that you do not need the US to maintain the pairing. This is the case since you have ran away, your brain thought that you have avoided the US = positive prediction
  • Conditioning also play a role in drug addition (besides all the biology happening)
    • Conditioned drug effects are common and demonstrate conditioning’s power
    • e.g. the smell of coffee can become a conditioned stimulus (CS). The smell alone can lead coffee drinkers to feel activated and aroused, as though they have actually consumed caffeine

Unlearning Conditioning

Once conditioned, can the conditioned response be eliminated/unlearned?

  • Extinction of CR - the gradual weakening and apparent disappearance of the conditioned response when the conditioned stimulus is repeatedly not presented with the unconditional stimulus
    • e.g. bell repeatedly not presented with food (negative prediction error)
    • e.g. however, PTSD is cannot be unlearnt
  • Spontaneous Recovery of CR - the phenomenon that after extinction of a CR, the immediate reappearance of the same CR (without the acquisition phase) due to the re-presentation of the original conditioned stimulus CS with the unconditioned stimulus.
    • e.g. after “unlearning” bell and food, once you re-presented bell and food again, the pairing might be recovered immediately.
      • then, if you pair that again, the pairing/conditioning comes back

In general, extinction can replace the associative bond, but it does not eliminate that bond (due to spontaneous recovery).

Effectiveness of Acquisition/Maintenance/Extinction

Below is, in one experiment, how the researcher designed three ways of pairing:

  • strong (orange): so that for $100\%$ of the time, NS or CS is presented with UCS
  • middle (blue): so that for $50\%$ of the time, NS or CS is presented with UCS
  • weak (red): so that for $25\%$ of the time, NS or CS is presented with UCS



  • each trial is composed of many attempts.
  • in the acquisition phase, it seems that all three pairings were successful (all acquisition were successful) after the second trial (if the successful acquisition is defined as $50\%$ of the elicited response)
    • the threshold of successful acquisition is defined by the researcher him/herself
  • in the extinction phase, the stronger the pairing, the faster the rate of extinction

Anatomical Changes of Classical Conditioning

Below discusses anatomical changes in the brain due to classical conditioning for different sense.

  • if a neuron is supposed to be activated by a specific chemical, but classical conditioning made it become activated due to other stimulus.
Gustatory Sense

For example, in terms of gustatory sense as UCR:

  • It is usually found that the Ventral tegmental area (VTA) are affected, as they are associated with emotion and the pleasure of food


  • Therefore, if we record the activity of neurons in the VTA before the acquisition phase:

    • here, we are pairing the flash of light with orange juice for a monkey


  • activity of the same neuron in the VTA after acquisition:


Olfactory Sense

In a mice, the part that deals with smelling is the olfactory bulb. And acetophenone is an “pleasant” odorant that activates neurons in the olfactory bulb of the brain.

  • Now, if you are paring the acetophenone with foot-shocking for the mice, it is found that:

    • after the acquisition phase, once acetophenone is presented, the mice did not feel pleasant but were “freezing” their body

    • in fact, it is found that:


      • more neurons now gets activated by acetophenone for the conditioned mice, some of which might be related to causing the “freezing” in the body
Long Term Potentiation

Long-term potentiation (LTP) is a persistent increase in synaptic strength due to high-frequency stimulation of a chemical synapse.

  • as as result, synapses that have undergone LTP tend to have stronger electrical responses to that stimuli than other synapses.

  • during conditioning, this means LTP can result in synaptic plasticity (anatomical changes of neurons near the synaptic area)

  • an example would be neuron forming a new dendritic spine which would increase synaptic efficacy of that stimulus


This also connects to how we form long term memory - learning and memory results from a forming/strengthening of synaptic connections between neurons that fire together.

  • As the synapse between two neurons strengthens during consolidation, the two neurons become better connected, as though a freeway had been built between them.

Contemporary Views of Classical Conditioning

In the above cases, two events/stimuli are presented in contiguity (i.e., together in time), and it would produce a learned association.

However, sometimes, classical conditioning tends to also choose its own neutral stimulus. (i.e. certain pairings of stimuli are more likely to become associated than others.)

  • for example:
    • Taste Aversion - a dislike for a particular food when an organism becomes ill hours after eating the food and that the exact cause for the illness is not clear
      • e.g.: A rat was offered two neutral stimuli: sugar water and many toys in a cage to play with
      • then, after 24 hours, it is injected with a drug causing gastrointestinal distress
      • finally, rat refused to drink the sugar water again, but still played with toys
    • Biological Preparedness - animals are genetically programmed to fear specific objects.
      • e.g. Monkeys can more easily be conditioned to fear snakes than to fear objects such as flowers or rabbits
      • e.g. when people participate in conditioning experiments in which aversive stimuli are paired with members of their own racial group or members of a different racial group, they more easily associate the negative stimuli with “outgroup” members
        • This finding indicates that people are predisposed to wariness of outgroup members.
  • this challenges the Pavlov’s principles of classical conditioning, in which you needed a defined time interval between between NS and UCS, and of course a clear causation relationship for pairing, because:
    • for food aversion, it is easy to produce conditioning with food (e.g. food + stomachache), but they are very difficult to produce with light or sound.
    • From an evolutionary viewpoint, this makes sense because animals that quickly associate a certain taste with illness, and therefore avoid that taste, will be more successful.


  • When doing classical conditioning, associations of a particular stimuli might be more likely to be paired with the autonomic response due to our innate disposition (hence relates to evolution theory)
    • e.g. if you got gastrointestinal distress, association is more likely to be formed with the food/drink NS

Learned Helplessness

Learned helplessness is behavior exhibited by a subject after enduring repeated aversive (unpleasant) stimuli beyond their control. It was initially thought to be caused from the subject’s acceptance of their powerlessness: discontinuing attempts to escape or avoid (giving up) the aversive stimulus, even when such alternatives are unambiguously presented.

  • For example: A child who performs poorly on math tests and assignments will quickly begin to feel that nothing he does will have any effect on his math performance. When later faced with any type of math-related task, even the ones he is fully capable of, he may experience a sense of helplessness and fail.

Operant Conditioning

Classical conditioning is a relatively passive and automatic process. Through classical conditioning, an animal learns predictive associations between stimuli, regardless of the animal’s behavior.

Operant conditioning is the learning process in which an action’s consequences determine the likelihood of that action being repeated.

The idea here is that that animals operate on their environments to produce effects

  • Thus, in operant conditioning, the human or animal makes associations between behavior and events that it can control. By contrast, in classical conditioning, the association is made between events that cannot be controlled.

  • A method of learning that occurs through rewards and punishments for behavior, which is voluntary (hence you can voluntary stop it as well).

Law of Effect

  • Before the term operant conditioning, this is what it is called: (by Edward Thorndike):
    • within an environment, when a voluntary behavior produces satisfying effects, this will likely occur again in the same environment, and vice versa for voluntary behavior producing a non-satisfying effect.
  • Later, this term becomes what is known now: operant conditioning.

Learning Through Reinforcement

Basically, Thorndike hypothesize that operant conditioning works by having a reinforcer - a stimulus (reward/punishment) that occurs after a response and increases the likelihood that the response will be repeated.

  • Positive reinforcement - giving some reward to the subject when they perform the desired action so they associate the action with the reward and do it more often. The reward is a positively reinforcing stimulus.
  • Negative reinforcement - avoiding/removing some punishments when they perform the desired action so they associate the action with the “reward” and do it more often. The punishment is a negatively reinforcing stimulus.


  • In both cases, both reinforcement increases the likelihood of behavior being repeated.
  • Positive punishment- giving some punishment to the subject when they perform the desired action so they associate the action with the punishment and do it less often. The punishment is a negatively reinforcing stimulus.
  • Negative punishment- avoiding/removing some reward to the subject when they perform the desired action so they associate the action with the “punishment” and do it less often. The reward is a positively reinforcing stimulus.


  • In both cases, both reinforcement decreases the likelihood of behavior being repeated.

Caveats in Using Punishment for Operant Conditioning

  • Research has shown that for punishment to be effective, it must be reasonable, unpleasant, and applied immediately so that the relationship between the unwanted behavior and the punishment is clear.
    • this is to avoid considerable potential for confusion
    • e.g. if a student is punished after admitting to cheating on an exam, the student may then associate the punishment with being honest (for admitting) rather than with the original offense. As a result, the student learns not to tell the truth.

Operant Conditioning Experiment

  • Operant Chamber/Skinner Box:
    • A box designed by Skinner, so that you can experimentally measure the relationship between operant (voluntary behaviors) and the consequences.


Using this setting, for animals, we can make them acquire or maintain their voluntary behaviors during operant conditioning, via any of the following ways:

  • Fixed-Ratio Schedule
    • reinforcement should be delivered after a constant or “fixed” number of correct responses.
      • For example, a fixed ratio schedule of 2 means reinforcement is delivered after every 2 correct responses.
  • Variable-Ratio Schedule
    • the delivery of reinforcement will “vary” but must average out at a specific number. Just like a fixed-ratio schedule, a variable-ratio schedule can be any number but must be defined.
      • For example, a teacher following a “VR2” schedule of reinforcement might give reinforcement after 1 correct response, then after 3 more correct responses, then 2 more, then 1 more and finally after 3 more correct responses.
      • Hence, overall there were a total of 10 correct responses (1 + 3 + 2 + 1 + 3 = 10), reinforcement was delivered 5 times and so reinforcement was delivered for every 2 correct responses on average (10 ÷ 5 = 2)
  • Fixed-Interval Schedule (FI)
    • A fixed-interval schedule means that reinforcement (reward/punishment) becomes available after a specific period of time.
      • this means that the reinforcement only becomes available to be delivered and would only be given if the target behavior is emitted at some stage after the time interval has ended.
  • Variable-Interval Schedule (VI)
    • Similar to the above, it refers to time periods that must pass before reinforcement becomes available. However, the time period will “vary” but must average out at a specific time period. Again the time interval can be any number but must be defined.

Partial-reinforcement extinction effect

  • Interestingly, ** according to experiments, **behavior under partial reinforcement (variable-ratio/interval schedule) persists longer than under continuous (fixed-ratio/interval schedule) reinforcement.
    • Makes sense because during continuous reinforcement, the learner can easily detect when reinforcement has stopped.


Sometime, during an experiment above, rather than wait for the animal to spontaneously perform the desired action, you can use an operant-conditioning technique called shaping to teach the animal to do so.

  • Shaping: The technique that consists of reinforcing behaviors that are increasingly similar to the desired behavior.
    • e.g. Suppose you are trying to teach your dog to roll over. You initially reward any behavior that even slightly resembles rolling over, such as lying down. Once this behavior is established, you reinforce behaviors more selectively. Reinforcing successive approximations eventually produces the desired behavior.

The key aspect to make shaping work is that animal learns to discriminate which behavior is being reinforced.


Using operant conditioning theory, superstition can be understood as the follows:

  • Some random actions were accidentally reinforced by a desirable output, which actually just occurred by chance.

    • The tendency to associate events that occur together in time is incredibly strong because the brain is compelled to figure things out.

    • e.g. wearing a “good luck sock” during an exam, and getting a good score

Aware of the tendency to associate events with other events that occur at the same time, it means you should distinguish yourself whether the timing was simply a coincidence, and then “risk” wearing different socks to your next exam!

Primary and Secondary Reinforcer

Basically, there are two categories of reinforce (rewards) that are used in operant conditioning:

  • primary reinforcers - food or water, because they satisfy biological needs.
    • therefore, if given those stimulus/reward, we would operant associate our behavior
    • Biologically, this make sense because animals that repeatedly perform behaviors reinforced by food or water are more likely to survive and pass along their genes.
  • secondary reinforces - Stimuli that serve as reinforcers but do not satisfy biological needs.
    • e.g. money, A for paper
    • therefore, if given those stimulus/reward, we technically need to first associated the reward to the primary reinforcer. Then, we would operant associate our behavior.
    • e.g. since money (CS) represent/associates food, security, power (UCS), which are primary reinforces, money as a reinforcer work, but as a secondary reinforcer

Reinforcer Potency

Some reinforcer (reward) are more powerful than others, and below would be a way to determine show potent a reinforcer is.

  • in short, you would want your operant conditioning to use a potent reinforcer

Psychologist David Premack theorized one measurement of measuring a reinforcer’s value:

  • the amount of time a person, when free to do anything, willingly engages in a specific behavior associated with the reinforcer.
    • e.g. most children would choose to spend more time eating ice cream than eating spinach. Ice cream is therefore more reinforcing for children than spinach is.
      • therefore, if you use ice cream as a reward to be given in your experiment, it will be more effective than giving a spinach
    • however, two things need to be taken care of in this method
      • reinforcer’s value can vary with context. (e.g. if you are full, and given ice cream)
      • reinforcer’s value can vary with different people (e.g. an adult might prefer eating spinach)

One important application of the above is the Premack principle.

Premark Principle

  • a more-valued activity can be used to reinforce the performance of a less-valued activity.
    • e.g. Parents use the Premack principle all the time. They tell their children, “Eat your spinach and then you’ll get dessert,” “Finish your homework and then you can go out,” and so on.
    • this means it will not be effective if you attempt to reinforce a behavior by something that is less-valued

Application of Operant Conditioning in Real Life

One useful case if for behavior modification

  • remove unwanted behaviors and replace them with desirable ones

To do this, consider the following steps:

  1. Identify a behavior you wish to change
  2. Set goals.
    • Set goals that are realistic, specific, and measurable
  3. Monitor your behavior.
    • Monitor your behavior for a week or more before you begin making changes.
    • You will use this baseline as a point of comparison later to assess your progress.
  4. Select a positive reinforcer and decide on a reinforcement schedule
    • pick something attainable that you genuinely find enjoyable
    • e.g. a movie each week that you meet your goal
  5. Reinforce the desired behavior.
    • To cause the behavior change you want to see, you need to reinforce the desired behavior whenever it occurs
    • e.g. This also means, if you do not work out at the gym three times this week (your goal), do not watch Grey’s Anatomy (your reinforcer).
  6. Modify your goals, reinforcements, or reinforcement schedules, as needed.
    • Once you begin consistently hitting your stated goals, make the goals more challenging.

Contemporary View of Operant Conditioning

In reality, however, reinforcement schedules explain only a certain amount of human behavior. Biology constrains learning, and reinforcement does not always have to be present for learning to take place.

Biological Constraint

For instance, animals have a hard time learning behaviors that run counter to their evolutionary adaptation.

  • For example: pigeons can be trained to peck at keys to obtain food or secondary reinforcers, but it is difficult to train them to peck at keys to avoid electric shock. They can learn to avoid shock by flapping their wings, because wing flapping is their natural means of escape.


  • The psychologist Robert Bolles (1970) has argued that animals have built-in defense reactions to threatening stimuli. Conditioning is most effective when the association between the response and the reinforcement is similar to the animal’s built-in predispositions.
Latent and Insight Learning

Namely, sometimes learning can take place without reinforcement.

  • Cognitive Maps/Latent Learning

    Basically, during the acquisition phase via the methods mentioned above, even if the subject/animal did not behave what you wanted, it might still be learning it cognitively.

    • Latent Learning - during acquisition of learning, cognitive maps are being formed, but they took place without reinforcement
      • hints at observational learning

    For example:

    • Consider three groups of mice in a maze:


    • and we see that for Group 3, the huge drop in the amount of errors they have means they might have learnt something extra as compared to the other groups, but have not demonstrated in their behavior

  • Insight Learning.

    • For example, during a problem solving, a solution suddenly emerges after either a period of inaction or contemplation of the problem.

The Role of Dopamine In Operant Conditioning

Similar to classical conditioning, the neurotransmitter dopamine here also plays a big role.

  • In operant conditioning, dopamine release sets the value of a reinforcer. Drugs that block dopamine’s effects disrupt operant conditioning.
  • Therefore, you could use this fact to:
    • Use drugs that enhance dopamine activation, such as cocaine and amphetamines, to increase the reward value of stimuli.
    • this is biologically like this. For instance food tastes better when you are hungry, and water is more rewarding when you are thirsty, because more dopamine is released under deprived conditions than under nondeprived conditions (i.e. the more you want it, the better you feel when you get it).

The above comes with an edge case: sometimes, wanting occurs without liking.

  • even in this case, the object might have been conditioned with a primary reinforcer in one way or another, hence becomes rewarding.

Week 8

Observational Learning

  • Learning that occurs through observing the behavior of others, including the consequences. As a result, you acquire or modify your behavior due to such an exposure.

For example:

  • Consider three groups of kid, each watching a version of a film:
    1. Adults punching Bobo doll, and given snacks and toys afterwards
    2. Adults punching Bobo doll, and being scolded afterwards
    3. Adults punching Bobo doll, and nothing happens afterwards
  • As a result:
    • kids after watching film 1 are more likely act aggressively to the Bobo doll
    • kids after watching film 2 are less likely act aggressively to the Bobo doll

This is also means a form of latent learning, as all the kids are just watching, yet learnt the behavior latently.

A related fact would be: watching violence would generally increase the children’s aggressiveness. This could be explained as they are desensitized to violence (Non-associative Learning), showing fewer helping behaviors and increased aggression


The imitation of observed behavior is called modeling. The term indicates that people are reproducing the behaviors of models-those being observed.

However, modeling in humans is influenced by numerous factors.


  • the most obvious ones would be: we tend to model actions of models who are attractive, have high status, and are somewhat similar to ourselves.
    • In addition, modeling is effective only if the observer is physically capable of imitating the behavior.

Vicarious Learning

  • whether observers imitate a model is whether the model is reinforced for performing the behavior.
  • e.g. the adult punching Bobo doll example

Difference between Observational/Associative Learning

  • It all about the difference between acquisition of a behavior and its performance. Here, all the children acquired the behavior. But only those who saw the model being rewarded performed the behavior.

Learning Fear Through Observation

People and animals are capable of learning to fear particular things simply by seeing/hearing that the things are dangerous.

  • this also has a biological constraint to it, so that you can be made easily fear things that you are biologically prepared to fear
  • e.g. monkeys can learn fear for snakes by watching other monkeys being fearful. They observationally learn this quickly because they are biologically programmed to learn to fear snakes
    • however, you cannot easily make them fear flowers, for instance


Memory - the abilities associated with encoding, storage (including consolidation), retrieving/recalling cognitive information, sensory information and sensorimotor information.

  • encoding phase occurs at the time of learning, as information is transformed encoding into a format that can be stored in memory
  • storage phase is the retention of the encoded representation. That is, a change in your nervous system registers what you just experienced, retaining it as a memorable event.
    • During the change, your neural connections that support memory become stronger, and new synapses are constructed. This neural process is known as consolidation. Through consolidation, encoded information becomes stored in memory.
  • retrieving stage consists of reaching into memory to find and bring to mind a previously encoded and stored memory when it is needed.

Reconsolidation of Memory

  • Basically, it is the theory that once memories are activated, they need to be consolidated again to be stored back in memory. These processes are known as reconsolidation.
    • think of this image: A librarian returns a book to a shelf for storage so that it can be taken out again later
    • This means our memory might change when we “use” them, such as when they are changed by our mood, knowledge about the world, or beliefs.
  • Reconsolidation happens each time a memory is activated and placed back in storage, and it may explain why our memories for events can change over time

In general, you can imagine our memory system similar to that of a computer:


Memory Model

![Information Processing Model (Three Box Model): Three Interacting… Download Scientific Diagram](https://www.researchgate.net/profile/Snejana_Dineva/publication/309487929/figure/fig1/AS:422099484450817@1477647767783/nformation-Processing-Model-Three-Box-Model-Three-Interacting-Memory-Systems.png)


  • you start with sensory inputs

  • sometimes, the term working memory is used instead of short term memory
  • before recalling information, you tend to retrieve them to your STM
    • this also means you recall information technically from STM

Sensory Memory

A very brief memory that allows people to retain impressions of sensory information after the original stimulus has ceased.

It is often thought of as the first stage of memory that involves registering a tremendous amount of information about the environment, but only for a very brief period.

  • e.g. look at something and quickly glance away, you can briefly picture the image and recall some of its details

  • One thing to note here is that, (for example) during our vision processing for reaching into sensory memory, we are also able to simultaneously process other sense as well (e.g. audition).

Remember that our sensory systems transduce, or change, that information into neural impulses.

  • So everything we remember from sensory is just the result of neurons firing in the brain

Thanks to sensory memory, when you turn your head, the scene passes smoothly in front of you rather than in jerky bits. Your memory retains information just long enough for you to connect one image with the next in a smooth way that corresponds to the way objects move in the real world.

Short Term Memory

To reach STM from sensory memory, we need to:

  • pre-attention
    • the ability of detection of a certain stimulus precede focused attention.
    • subconscious accumulation of information from the environment. All available information is pre-attentively processed.
  • which leads to sensory gating
    • Then, the brain filters and processes what is important. Information that has the highest salience (a stimulus that stands out the most) or relevance to what a person is thinking about is selected for further and more complete analysis by conscious (attentive) processing
    • sometimes also referred to as selective attention
  • which leads to STM
    • in which Information remains for about 20 to 30 seconds. It then disappears unless you actively prevent that from happening (e.g. via consolidation)

For example:

  • suppose you see a flash of picture, on which there are some blue dots but only one red dot.
    • your brain hasn’t let you focus on this, so all the below processing would be subconscious
  • your pre-attention ability will detect some blue and the red dot on the picture, and pass it to your brain
  • your sensory gate will filter out some irrelevant information, maybe things like how red the red dot is
  • finally, at least some information after your gating will come into your STM, in which you might recall that you see a red dot


  • Similar to sensory memory, researchers learned that short-term memory is not a single storage system. Instead, it is an active processing unit that deals with multiple types of information.

Prepulse Inhibition

This could be potentially a way of measuring the strength of our STM.

Prepulse inhibition (PPI) is a neurological phenomenon in which a weaker prestimulus (prepulse) inhibits the reaction of an organism to a subsequent strong reflex-eliciting stimulus (pulse), often using the startle reflex.

  • startle response: defensive sensorimotor response due to a sudden, intensive response

For example



  • the length of time from your prepulse to the actual pulse, such that you receive a reduced response, will be indicative of your ability of STM
    • if after a long time, you send a pulse, and you get a startle response, that means your STM forgot the prepulse

However, the ability to have prepulse inhibition vary, such that:



  • it suggests that people diagnosed with schizophrenia tend to have less inhibition if pre-pulse comes too early

Sensory Gating

It is basically related to our ability of selective attention:

  • process of directing our awareness to relevant stimuli while ignoring irrelevant stimuli in the environment.
    • For example: the cocktail party effect is the phenomenon of the brain’s ability to focus one’s auditory attention (an effect of selective attention in the brain) on a particular stimulus while filtering out a range of other stimuli, as when a partygoer can focus on a single conversation in a noisy room.

Short Term Memory Span and Chunking

STM is the mental process that enables us to temporarily recall cognition.

  1. Why do new items in our STM interfere with old items that was there?
    • this is mainly due to the duration/capacity of STM being limited (could be as few as four items)
    • in general, limit is generally seven items (plus or minus two), and this figure is referred to as memory span
  2. But sometimes, we are able to hold more “items” than our memory span.

    • e.g. remember the word BCPHDNYUMAUCLABAMIT as BC,PHD, NYU, MA, UCLA, BA, MIT

    • this is because of the phenomena of chunking - process of breaking down information into meaningful units. The more efficiently you chunk information, the more you can remember.
    • in short, organization makes them much easier to recall

Long Term Memory

In the computer analogy presented earlier in this chapter, long-term memory is like the storage of information on a hard drive.

  • however, LTM in human is actually more powerful, as it is nearly limitless!

In short, LTM, as compared to STM, has a longer duration, and it has a far greater capacity.

Distinguishing LTM and STM

Besides capacity and duration, there is an interesting phenomenon that can help distinguish the two:

  • serial position effect, where you tend to recall the earliest and the latest items in a list the best, but worst at the middle



  • This effect actually consists of two separate effects:
    • The primacy effect refers to the better memory that people have for items presented at the beginning of the list.
      • this is actually because people tend to rehearse (consolidate) the earliest information (to LTM)
    • The recency effect refers to the better memory that people have for the most recent items, the ones at the end of the list
      • this is because they are still in our short-term memory

This means delay between the presentation of the list and the recall task could interfere with only recency effect (as they are in STM), but not with primary effect.

Still, the two memory systems (STM and LTM) are highly interdependent, at least for most of us. For instance, to chunk information in working memory, people need to form meaningful connections based on information stored in long-term memory.

Encoding Long Term Memory

Basically, short term memory gets encoded to become long term memory


where encoding processes for STM to LTM include the following:

  • maintenance - simply repeating the item over and over.
    • i.e. hard-coding the information into LTM
    • this is not very efficient in general
  • elaboration - process by which one cognitively applies meaning to the information by linking it to knowledge from long-term memory.
    • i.e. adding elaboration information to an encoding
  • organization - the process by which one cognitively applies individual objects as one meaningful item, rather than as separate items, to this encoding
    • i.e. adding organizational information to an encoding

In short, if you want to store the information in LTM, you need to store it in a way that enables you to retrieve it later.

In general, the more deeply an item is encoded, the more meaning it has and the better it is remembered.

  • such an encoded information is sometimes also known as a mental representation

Then, the actual encoding/storing mechanism is the:

  • consolidation - the process by which labile (unstable) LTM is converted to stable LTM (the actual encoding)
    • i.e. actually encoding/storing the information


Elaboration is the process that involves changing or adding to material, or making associations to make remembering a material easier.

For example:

  • If you are given a list of words to remember, and you used the following three ways to do it:
    • only looking at the words
    • listening to the pronunciations of the words
    • making personal meaning of the words
  • In the end, it terms out that after 2 weeks (hence LTM), participants making meaning of them recalled the most words


Organization is the process by which one cognitively applies individual objects as one meaningful item, rather than as separate items, to the encoding.

  • As a result, by forming connections on the organization of the items, it makes the content more memorable.

For example:


  • would be easier to remember by MD PHD RSVP CEO IHOP, and trying to associate each organization.
  • this is essentially the idea of chunking information as discussed before

One important question here is: how do our brain decide how to chunk?

Decisions about how to chunk information depend on schemas - cognitive structures in long-term memory that help us perceive, organize, process, and use information.

  • schemas guide our attention to an environment’s relevant features, and provide structures/context for understanding events in the world.
  • e.g. you have a schema for grocery shopping at markets in the United States. That schema most likely includes shopping carts, abundant choices, and set prices. You may expect to choose your own fruit and vegetables in the produce section

However, this also means schemas can bias how information is encoded.

  • This bias occurs in part because culture heavily influences schemas


Consolidation is the process of converting of labile LTM/STM to stable LTM, thus encoding stable LTM.

  • for example, converting the previous sequence of words into stable LTM

In fact, as you will see in the section of **Explicit/Implicit LTM, hippocampus is actually for encoding **explicit LTM. Implicit LTM will be intact if hippocampus is removed.


  • Labile LTM generally involves neural activity within the hippocampus
  • Stable LTM generally involves neural activity within the frontal lobe (one part of the frontal lobe is the prefrontal cortex)



  • consolidation would mean converting information from your hippocampus to your frontal lobe


  • However, there can be many different ways of consolidating the information.
    • One simple way would be to revisit the content regularly.
    • Another more efficient way includes practicing retrieval
    • Rehearsal is a way to get some information into long-term memory, but simply repeating something many times is not a good method for making information memorable
  • It also means that, the removal of hippocampus means the lost of ability of encoding STM to LTM. This means you cannot encode new LTM.

Anatomical Changes for Long Term Memory

What happens in the brain when a memory has been consolidated to be long term?

In short, the answer is:

  • long-term storage of information results from the development of new synaptic connections between neurons. In other words, memory involves the creation of neural circuits

Long Term Potentiation - LTM

This has been addressed in the associative learning chapter (see Long Term Potentiation), and it certainly also works here.

  • Long-term potentiation (LTP) is strengthening of a synaptic connection, making the postsynaptic neurons more easily activated by presynaptic neurons.
    • LTP serves as a model of how neural plasticity might underlie memory (and learning)



  • As the synapse between two neurons strengthens during consolidation, the two neurons become better connected, as though a freeway had been built between them.
    • i.e. consolidation $\iff$ intense and frequent pulses in stage (2)
    • i.e. established LTM $\iff$ two neurons being better connected in stage (3)

Detailed Mechanism Behind LTP

A critical player in LTP is the NMDA receptor on the postsynaptic neuron, which is basically a glutamate receptor.

And this is what happens:

  • LTP leads to an increase in the number of glutamate receptors on the postsynaptic neuron
  • which increases its responsivity to glutamate released by the presynaptic neuron.
    • It can also produce more synapses between neurons.
  • it means the postsynaptic neuron is more easily activated by the presynaptic neuron
  • So it is strengthening synaptic connections among networks of neurons

ASK: I thought it should only strengthen particular synaptic connections

Extension: Drug that could Improve LTM

  • Research shows that blocking HDAC (histone deacetylases, an enzyme) leads to increased memory.
  • The general idea is that HDAC serves as a molecular “brake”, which has to be released from the molecule for memory to occur. However, unless something critical happens in the environment, the molecular brake is on and nothing is stored in memory.
    • This means drugs that block (turn off) HDAC lead to increased LTP. (e.g. drug that activate NMDA receptors)

Long Term Potentiation via Genes

In short, the idea is that a gene (which has the ability to control everything going on in a cell) could also be notified to establish connections between two neurons:



  • It starts by the phase of acquisition of new information, where serotonin molecules goes to bind to receptors embedded in the dendrites of the postsynaptic neuron to open the receptor to allow an influx of Na+.
  • This triggers the CRE on the gene, which is a transcribing factor for telling the gene which part associated with LTP to transcribe
  • The triggering will usually cause the transcription of a gene called ubiquitin hydrolase, which is highly implicated for LTM. Therefore, this ubiquitin pathway is implicated for the formation of “memory neurons”.
  • As a result, the binding of serotonin to its receptor of this neuron is no longer needed because there is persistent activation of PKA for the expression of the ubiquitin pathway

Anatomical Regions for LT Memory

We know that hippocampus is for encoding new explicit LTM, but where is our LTM stored (where does LTP happen)?

In short, it turns out the storage of memory is distributed among our brain:

  • temporal lobes are important for being able to say what you remember
  • cerebellum is involved in memory for motor actions
  • visual information is stored in the cortical areas involved in visual perception
  • …etc.



  • the role of medial temporal lobe is to form links, or pointers, between the different storage sites (e.g. vision and audition), and it direct/help the gradual strengthening of the connections between these links
    • Once the connections are strengthened sufficiently through consolidation, medial temporal lobes become less important for memory


  • memory is distributed among different brain regions. Memory does not “live” in one part of the brain
Dementia and Alzheimer’s Disease

Both relates to deficits in one’s STM, and one’s LTM.

  • This means that the neuroactivity of the temporal lobe are significantly reduced
  • As well as some other storages for LTM and STM



  • blue part indicates active neuroactivity

Retrieving Long Term Memory

Basically, this is the reverse process of encoding.

Retrieval is cognitively accessing one’s LTM to STM, demonstrated by recall.

To understand how retrieval works, we need to first understand how memory is stored on a high level

Association Network in LTM

This is a high level model of explaining how LTM works. For biological details, go to the section Anatomical Changes for Long Term Memory

This model is called spreading activation model, and the idea is as follows:

  • memory organization is based on networks of associations.
  • an item’s distinctive features are linked so as to identify the item
  • each unit of information (e.g. distinctive feature) is a node
  • The resulting network is like the linked neurons (nodes) in your brain, but nodes are simply bits of information.



  • An important feature of this mode is that activating one node increases the likelihood that closely associated nodes will also be activated (see Long Term Potentiation - LTM)

Retrieval Cues

A retrieval cue can be anything that helps a person (or a nonhuman animal) recall a memory

The idea behind retrieval cues is the encoding specificity principle:

  • any stimulus encoded along with an experience can later trigger a memory of the experience

Examples of retrieval cues include:

  • retrieval cues in context-dependent memory
    • this refers to memory being most easily recalled when recall situation is similar to the encoding situation
    • e.g. studied something in a specific room, and recall in the same specific room
  • retrieval cues in prospective memory
    • prospective memory is future oriented memory
    • For example, seeing Juan might automatically trigger your memory (which was to bring a message to Juan - future oriented memory), so you effortlessly remember to give him the message
  • mnemonics as retrieval cues
    • learning aids or strategies that use retrieval cues to improve recall.
    • e.g. memory palace, this mnemonic consists of associating items you want to remember with physical locations.
    • e.g. associate your classmates’ names with the items or parts you have visualized. You might picture Justin climbing on your dresser, Malia sitting on a chair, and Anthony hiding under the bed. When you later need to remember the names, you would visualize your room and retrieve the information associated with each piece of furniture

Study Technique Using Retrieval Cues

  1. Elaborate the material
    • think about how the word is relevant to you. For example, you see the word rain and think, “My car once broke down in the middle of a torrential rainstorm.”
    • Think about the meaning of the material and how the concepts are related to other concepts.
  2. Practice retrieval
    • practice retrieving the information you are trying to learn.
  3. Use verbal mnemonics for rote memory
    • learn long lists of items, but understanding the items doesn’t matter. In these cases, verbal mnemonics can help.
    • e.g. students have long used acronyms to remember information, such as HOMES to remember the great lakes (Huron, Ontario, Michigan, Erie, and Superior)
  4. Use visual imagery
    • a mental image of material may help you. Visual imagery strategies include doodling a sketch to help you link ideas to images
    • e.g. a flow chart or a concept map


  1. Association by contiguity - when a LTM is retrieved, another continual and contextual LTM will also most likely be retrieved
    • e.g. recalling the position of a spoon, also recalled the position for a knife
  2. Association by similarity - LTM can be linked, despite whether one has personal experience with this linking

Biological Basis of LTM

Long Term Memory Systems

Basically, we see long-term memory as composed of several interacting systems. These systems share a common function: to retain and use information. However, they encode and store different types of information in different ways


Explicit/Implicit LTM


The two broad category of LTM can be classified as

  • explicit (declarative) LTM - memory that needs conscious retrieval of cognition from LTM (i.e. we can explain why we know this)
    • episodic LTM - the conscious retrieval of specific events, situations, and experience, from your stable LTM.

    • semantic LTM – the conscious retrieval of “factual” cognition (ideas and concepts that are not drawn from personal experience) from stable LTM

  • implicit (non-declarative) LTM - memory that supports unconscious retrieval of cognition from LTM (i.e. we cannot explain why we know)
    • procedural memory – the unconscious retrieval of the performance of tasks (knowing how to do things) from stable LTM
      • involves motor skills, habits, and other behaviors
      • e.g. mirror tracing (tracing a pattern while looking at a mirror)
    • emotional memory – the unconscious retrieval of experiences that evoked an emotional reaction from stable LTM

Week 9

Flaws of LTM

We forget far more than we remember. You might also have memories that are false, such as remembering a particular person was in a film when she wasn’t or getting plot details wrong.

In short, human long-term memory systems provide less-than-accurate portrayals of past events


You can say that forgetting is an inability to remember. However, normal forgetting helps us retain and use important information.

  • on the contrary, if you could remember everything, you might experience a problem of recalling a specific thing among those memory

In general, even if you think you have forgotten things, they are not completely gone in your brain:

  • You may remember very little of the Spanish or calculus you took in high school, but relearning these subjects would take much less time and effort

  • The difference between the original learning and relearning is called savings. In other words, you save time and effort because of what you remember.

In short, forgetting something could happen on various causes, such as:

  • memory decay
  • blocking
  • absent-mindedness
  • amnesia

Memory Decay

Memory decay involves forgetting overtime.

While you might think you forget because those are unused memories, most forgetting occurs because of interference from other information.

  • proactive interference
    • old information inhibits the ability to remember new information.
    • For instance, if you study for your psychology test, then switch to studying for your anthropology test, and then take the anthropology test, your performance on the test might be impaired by your knowledge about psychology
  • retroactive interference
    • new information inhibits the ability to remember old information.
    • For instance, when it comes time to take the psychology test, your performance might suffer because you recall the freshly reinforced anthropology material instead



e.g. you “blank” on some lines when acting in a play, and so on. Such temporary blockages are common and frustrating.

  • Blocking occurs when a person is temporarily unable to remember some specific thing, but knows what it is about

Blocking often occurs because of interference from words (for example) that are similar in some way, such as in sound or meaning, and that recur.

  • For example, you might repeatedly call an acquaintance Margaret although her name is Melanie.


Absentmindedness is the shallow encoding of events. The major cause of absentmindedness is failing to pay attention.

  • For instance, you absentmindedly forget where you left your keys because when you put them down, you were also reaching to answer your phone.
  • e.g. recall that when prospective memory fails, you fail to remember to do something. Often, this form of absentmindedness occurs because you are caught up in another activity.


Some people lose the ability to retrieve vast quantities of information from long-term memory. This condition is called amnesia.

Usually, amnesia is caused by diseases or brain damage:

  • anterograde amnesia – after damage to the brain (or surgery to remove part of the brain), there is decreased ability to encode new information from one’s STM to LTM, thus decreased ability to recall this type of cognition for one’s STM
    • e.g. Patient H.M. removed his hippocampus, and caused this anterograde amnesia
  • retrograde amnesia – after damage to the brain (or surgery to remove part of the brain), there is decreased ability to retrieve from stable/encoded, old information in LTM, thus, decreased ability to recall this type of cognition for one’s STM


Brain not only have the flaw of forgetting things that you need, it also has the flaw of not being able to forget things that you want to forget.

  • Persistence occurs when unwanted memories are remembered in spite of the desire not to have them.
    • e.g. PTSD

Reducing Persistence

In short, the persistence memory are usually the fearful and traumatic ones. There has been three ways to deal with it:

  • Using the drug - propranolol: it blocks the postsynaptic receptors for the neurotransmitter norepinephrine.
    • if given right before or after a traumatic experience, response for the hormonally enhance memories are reduced, and the effect lasts for months
    • however, there might be side effects
  • Using the technique - extinction
    • during the reconsolidation phase, use the technique of extinction
    • no side effect
  • Using HDAC inhibitors: they removes the molecular brakes on memory. As mentioned before, turning off HDAC improves LTP, hence could make reconsolidation powerful enough to erase old memories and replace it with a new (non-traumatic) version.
    • By inhibiting HDAC during the reconsolidation of a memory in a nonhuman animal, researchers were able to reduce an old conditioned fear response
    • the problem with is approach is that it is too effective. Ethical concern on wiping/replacing memory.

Memory Bias

This talks about the problem of your memory sometimes being wrong.

  • The changing of memories over time so that they become consistent with current beliefs or attitudes

    • This means that, often, people revise their memories when they change attitudes and beliefs.

    • People also tend to remember events as casting them in prominent roles or favorable lights.

      • hence the problem of eyewitness testimony that confirms their beliefs, instead of what actually happened

      • e.g. they might remember certain types of people are more likely to commit crimes and therefore might be more likely to identify people with those characteristics as the likely criminal

Flashbulb Memories

A flashbulb memory is a highly detailed, exceptionally vivid ‘snapshot’ of the moment and circumstances in which a piece of surprising and consequential (or emotionally arousing) news was learned about.

  • Although flashbulb memories are not perfectly accurate, they are at least as accurate as memory for ordinary events. As mentioned earlier in this chapter, to the extent that emotion is associated with an event, it tends to be better remembered
  • The key takeaway is that: even though peoples’ memory/emotion/belief might change, what does not seem to change is the extent to which people feel confident in their memories.
    • Indeed, people are more confident about their flashbulb memories than they are about their ordinary memories
    • Explains why you are sometimes so confident but your memory is just wrong

Source Misattributions

This talks about memories being partially wrong, but for the important parts that might cause confusions.

  • Source misattribution occurs when people misremember the time, place, person, or circumstances/context involved with a memory
  • e.g. you see an online ad for a way to learn French while you sleep. You probably will not believe the claims in the ad. Yet over time you might remember the promise content but fail to remember the source. Because the promise occurs to you without the obvious reason for rejecting it, you might come to believe that people can learn French while sleeping, or you might at least wonder if it is possible.

They are two forms of source misattributions:

  • Source amnesia is a form of misattribution that occurs when a person has a memory for an event but cannot remember where he or she encountered the information.
  • Cryptomnesia is the phenomenon that a person thinks he or she has come up with a new idea, but instead, the person has retrieved an old idea from memory and failed to attribute the idea to its proper source

Suggestibility Biased Memory

This refers how our memory can be easily tweaked based on the technique of suggestibility.

  • people can develop biased memories when provided with misleading information, which is known as suggestibility.
    • e.g. The different wordings of the questions altered the participants’ memories for the event.

There are multiple ways to use the technique of suggestibility:

  • According to the spreading activation model, related information produce overlapping patterns of brain activity in the very frontmost portion of the temporal lobe. Those activations could cause participant confusion on what was actually confused, as they are all overlapping.
    • therefore, you tend to best recall the main theme (overlapped part), instead of tracing back to recover each individual information

Repressed Memories

This basically talks about the problem of whether knowing a piece of memory being:

  • repressed memory, and resurfaced just now
  • memory that has been faked by suggestibility

In short, both have happened, and it was a heated debate

Week 10



Language is a system for the effective use of signals to convey meaning so that we can communicate with each other.

The system of language can be decomposed into:



  • Phonemes – smallest units of sound recognizable as speech
  • Morphemes – phonemes are combined to make meaningful units of language
    • Each word consists of one or more morphemes. Besides the root of a word, morphemes including suffixes and prefixes.
      • content morphemes - the root of the word, has a concrete meaning
      • function morphemes - the suffixes/prefixes
    • e.g. consider the words frost, defrost. The root word, frost, is a (content) morpheme. The meaning of this morpheme is changed by adding the prefix de, which is also a (function) morpheme.
  • Syntax - system of rules that govern how words are combined into phrases and how phrases are combined to make sentences
  • Semantics - meaning of syntax (phrases and sentences)
  • Pragmatics - how meaning/semantics might be changed due to context or intent.
    • An example of pragmatics is how the same word can have different meanings in different settings.

Sounds of Language

This talks about:

  • how we are able to physically speak a language

    • First, it works by forcing air through the vocal cords, which causes vibration of mucous membranes (part of larynx), hence producing sound
    • Then, vibrating air molecules passes from the vocal cords to the oral cavity (part of the mouth behind the teeth and above the tongue). There, jaw, lip, and tongue movements change the shape of the mouth and the flow of the air, further altering the sounds produced by the vocal cords.
    • image-20201109163535013
  • how we are able to separate words in a phrase/sentence for parsing

    • since languages also differ in the patterns of morphemes within phrases (a waveform). Such patterns help us separate the words we hear in conversation.

    • once we separated the stream of waveforms into segments, we parse its meaning

    • e.g. the waveform of “what do you mean?”:


Language in the Brain

In short, this is where your brain processes and produce language:

  • left hemisphere - this is the most important part of language

    • where you produce and comprehend language
    • Broca’s Area - used for producing a language
      • without/damaging Broca’s Area, you will experience expressive aphasia (also called Broca’s aphasia), which interrupts their ability to speak. These individuals generally understand what is said to them, but they cannot form words or put one word together with another to form a phrase
    • Wernicke’s Area - used for understanding/parsing a language (e.g. speaking)
      • without/damaging Wernicke’s Area, you will experience receptive aphasia (also called Wernicke’s aphasia), in which they have trouble understanding the meaning of words. This means they are not able to parse incoming language neither produce language that makes sense


  • right hemisphere

    • less important but still important
    • processing rhythms of speech, understanding metaphors

Capacity to Learn a Language

The first step of language acquisition (learning a language) involves starting to understand a language. But how do we parse the very language we are speaking?

  • surface structure - In language, the sound and order of words.
  • deep structure - In language, the implicit meanings of sentences.

And the idea is as follows:

  • people automatically and unconsciously transform surface structure to deep structure - the meaning being conveyed. In fact, people remember a sentence’s underlying meaning, not its surface structure.
    • also means when we generate a sentence, we might start with generating the deep structure
  • All language must be governed by universal grammar. In other words, according to Chomsky, all languages are based on humans’ innate knowledge of a set of universal and specifically linguistic elements and relationships
    • e.g. All languages include similar elements, such as nouns and verbs
  • According to Chomsky, humans are born with a language acquisition device, which contains universal grammar. This hypothetical neurological structure in the brain enables all humans to come into the world prepared to learn any language

Many errors associated with language result from interpretative differences between the deep structure of a sentence, even if the surface structure is the same (same sentence).

Bilingualism versus Monolingualism

Would learning a new language hinder the ability/development of the native language?

  • In short, according to research recently, learning a second language increases the density of grey matter in the inferior parietal lobe of the brain, and this increase is correlated with: a) attained proficiency of the second language, b) the age of the second language acquisition.
    • increasing density of grey matter means less energy would be needed for a certain part of brain to do its job. Hence, this indicates the increased ability to
      • parallel processing
      • serial processing



  • more proficient in second language means greater density in grey matter
  • earlier acquisition of second language means greater density in grey matter

Non-human Primates “Learn” Human Languages

Can other non-human primates “learn” human languages?


And the experiment went to:

  • Attempt to teach the ape verbal English
    • failure, problems with vocal chords
  • Attempt to teach the ape sign language
    • success
    • e.g. made signals for food


What does it mean to be intelligent?

  • Henry Goddard invented “intelligence” tests for identifying “feebleminded” individuals, for sterilization processes
    • which means eugenics - belief that the human race can be improved by manipulating which people are allowed to breed (intelligent breeds with intelligent only)
    • obviously, very unethical

History of Intelligence Tests

  • 1905

    • wanted to separate the difference between natural intelligence and education intelligence
    • developed test on both

    • Stanford university comes in and developed/formalized the intelligence quotient (IQ) (Stanford Binet IQ Test)

      • Categories of cognition being tested:

        • Fluid reasoning

        • Knowledge

        • Quantitative reasoning

        • Visual-spatial processing

        • Working memory

      • results:



        • test will be different based on different ages

Applications of Intelligence Tests

Used for detecting/assessing Intellectual Developmental Disability (IDD) (defined by the DSM V, where all the mental disorders are defined), or mental retardation as previous terminology in DSM IV, have evolved from their predecessors to include three key features:

  1. significantly subaverage intellectual functioning (IQ of 70 or below, allowing for measurement error)

  2. substantial impairments in adaptive functioning

  3. onset(发病) prior to adulthood

General Intelligence

General intelligence involves “directive cognition”, means you can cognitively direct your thoughts towards your goals, for example.

Also, there are different types of intelligence as well:

  • critical thinking – cognitions that evaluate evidence (Ellen Langer)
    • motivated to find the best solutions to tasks
    • criticism - schools spend too much time getting students to give a single correct answer in an imitative way
  • creative thinking – cognitions that are novel and unusual; unique solutions

Excelling at one type of cognition is likely to excel in other types of cognition.

Factor Analysis for Intelligence

Then, there comes the idea that Intelligence is not necessarily “measured”, but rather, intelligence is based on performance on tasks

  • Charles Spearman (early 1900’s) coined a statistical technique known as factor analysis, to help explain correlations between intelligence and performance
  • If intelligence is a single, general ability for performance, then there should be a strong, positive correlation between performance on all tasks



  • Multi factor basis of intelligence – general intelligence requires a combination of performance of all categorical abilities, and of all specific skills
    • But, just because someone has the highest performance on “solving logic problems”, this does not mean they also have the highest performance on “making legal arguments”

Week 11

Exam 3 Material Starts From This Line | Reading starts with Chapter 10

Human Development

Human development can be defined as the orderly and sequential changes that occur with the passage of time as we evolve from conception to death. i.e. looking at changes, over the human life span, in physiology, cognition, emotion, and social behavior.

  • studies how people grow, develop and adapt at different life stages

And in more details, this section studies:

  1. Physical pattern of growth - changes in nervous systems

  2. Cognitive pattern of growth - changes on information processing

  3. Social pattern of growth - changes on interactions with self and others

Note that these patterns of growth:

  • emphasize/assumes the “normal” processes or markers associated with aging and/or senescence
    • e.g. not considering the process of someone who got like a PTSD
    • this also allows us to define what would be abnormal properties of human development
  • are all interrelated

Abnormal Developments

The case of Gini, who has been captivated in her room for more than 10 years.

Her therefore strange behavior could be indicative of her abnormal brain development:



  • the process of pruning did not happen much
  • little proliferation of neurons/dendrites

Developmental Lifespans

In short, we can divide the entire lifespans into the following stages:

  • Prenatal: (conception to birth)
  • Infancy/Toddlerhood: (until age 2)
    • rapid growth of brain/cognitive/physical capacity
  • Early Childhood: (ages 3-6)
  • Middle Childhood: (ages 7-11)
  • Adolescences: (ages 12-18)
    • puberty
  • Emerging Adulthood: (ages 19-25)
    • newly identified lifespan
    • first transitioning into adulthood, where you take responsibilities of yourself
  • Adulthood: (ages 26-65)
  • Late Adulthood: (ages 66 and over)

And it is important that for each lifespan, there are key “developmental events” associated with them.

Cellular senescence:

  • The reason why we age and some of our cells stop functioning is because of telomere:



    • every time when a cell divides, the tip of the chromosomes (telomere) gets shorter. Once telomere is depleted, the cell cannot function anymore.
    • As a result, you age.

Common Experimental Methodologies

Some common methodologies taken place in developmental psychology include:

  • Longitudinal experimental methodology - data is collected over time, usually years, from the same group of individuals, as categorized by a cohort (group of individuals who have common characteristics such as age)
    • i.e. repeated observations of the same variables
  • Cross sectional experimental methodology - data is collected instantly from a group of individuals, as categorized by a cohort.
    • i.e. a snapshot of a particular group of people at a given point in time.
    • usually quicker than longitudinal methodology
    • may not reflect time and culture of the participants/cohorts
  • Cross sequential experimental methodology - data is collected over time, usually years, from different groups of individuals, as categorized by a cohort.
    • i.e. repeated observation and comparison of different variables
    • e.g. two or more groups of individuals of different ages are directly compared over a period of time


Prenatal Lifespan

The key stages here include:

  • Germinal Stage - conception to the end of 2nd week
    • formation of zygote
  • Embryonic Stage - beginning of the 3rd week to end of 8th
    • formation of embryo
  • Fetal Stage - beginning of 9th week to birth
    • formation of fetus

Germinal Stage

The important events here as basically:

  • fertilization
  • mitosis
  • implantation



  • sperm penetrates the egg cell to form a fertilized zygote
  • mitosis is the process of self-duplication
  • blastocyst is a structure formed in the early development of mammals.
  • implantation happens in the uterus

Embryonic Stage

After the germinal stage, everything happens inside the uterus. Some key events here are:

  • rapidly developing CNS related structure, especially your brain



  • therefore, this is the stage that is most susceptible to toxins, due to the rapidly development of structures associated with CNS.

Fetal Stage

As compared to the embryonic stage, here we are developing lateral structures of human body, such as limbs.


Prenatal Brain


Sexual Differentiation

Sexual differentiation is the process by which individual develop biological male bodies or female bodies

In terms of chromosomes:

  • For the 23rd pair, we receive an $X$ chromosome from our father, and either an $X$ or a $Y$ from our mother.
    • Females have a pair of $X$ chromosomes (46, $XX$), whereas males have one $X$ and one $Y$ chromosomes (46, $XY$).
  • As a result, during the first month of the prenatal lifespan, we develop our gonads: an organ that produces gametes; a testis or ovary.

**However, **things can still go wrong:

Turner’s Syndrome:

  • Instead of a pair of chromosome, you have only one: $X$ instead of $XX$. This only occurs to biological females.
    • As a result, it causes a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects

Classical Congenital Adrenal Hyperplasia

  • $XX$ with deficient enzyme that increases testosterone production during prenatal lifespans
    • as a result, development of both male and female gonads

Androgen Insensitive Syndrome

  • $XY$ with incapability of of producing functional testosterones receptors, or resistant to male hormones (called androgens)
    • As a result, the person has some or all of the physical traits of a woman, but the genetic makeup of a man.

Infancy/Toddler Lifespan

Recall that this is birth to 2 years, and some key events are:

  • Physical Patterns of Growth

    • generation of neurons in brain (approx. until 1 month)
    • proliferation/pruning of dendrites (approx. until 2 years)


  • Cognitive Patterns of Growth
    • infants can differentiate between different shapes
      1. using habituation, such that infants should decrease their time on looking at something new as we present it many times
      2. then, using dishabituation, we show them a different card, such that their response/time looking at it will increase
      3. it must then be that they can differentiate between two different shapes as different stimuli
  • Social Patterns of Growth
    • Importance of contact for attachment, not only the need for survival
    • contact for attachment has implications for both interpersonal traits, and intrapersonal traits
      • experimented using infants monkey being placed with a wired fake monkey providing milk + cloth fake monkey providing comfort
      • results show that those infant monkeys become more attached to monkey providing comfort

Early Childhood Lifespan

Around age 3-6.

  • Cognitive Patterns of Growth

    • Jean Piaget hypothesized that this is associated with preoperational stage (cannot think logically, but intuitively) of cognitive development.

      • experiments on testing children on the knowledge of “conservation”


      • flawed, because no motivation + they are only given the choices of which one is more
    • reasonably good STM and LTM, and strong resistance of suggestibility

      • experimented with making children experience a staged event of Mrs. Baker baking cookies
      • then, they are asked questions to recall the situation, and suggestibility has been used to try to distort their memory
      • as a result, it means early children are more resistant to “suggestibility biased memory”
  • Social Patterns of Growth

    • Lawrence Kohlberg first studied “moral development” in children, which helps understanding the social patterns of growth for early childhood children

    • children were already capable for moral reasoning, and in fact, it is mostly associated with the area of frontal lobe

      • experimented with giving children moral questions to answer

        • tested moral personal questions (involving yourself)
        • tested moral impersonal questions (not involving yourself)
        • tested non-moral questions (not related to morality)


        where we see:

        • frontal lobe associated with moral reasoning


(new chapter)

A process that energizes, guides, and maintains behavior toward a goal.

And motivation has been identified to be associated with three “forces”:

  • activation - initiation of the cognitive and behavioral processes for obtaining the motivated goal
    • e.g. bought new shoes for the upcoming marathon
  • persistence - continued cognitions and behavior to obtain and motivated goal, even in the face of obstacles
  • intensity - continued cognitions and behaviors, in relation to obtaining and motivated goal

Need Hierarchy

Maslow believed that people want to reach their personal “self-actualization”.

  • Self-actualization: attainment of the motivated goal, at a state that is achieved when one’s personal dreams and aspirations have been attained.
  • Need: something that is vital, at a state of biological or social deficiency.



  • Maslow believed that people’s need goes from bottom to top in a dependency manner, such that without fulfilling basic needs, you won’t even think about psychological needs.
  • Later research has shown, however, such a jump in needs could be possible for humans, i.e. needs are not hierarchical

Basic/Biological Needs

Motivations vital for survival.

Since our body strive for homeostasis (the state of steady internal, physical, and chemical conditions maintained by living systems), we need the following mechanisms:

  • Thermoregulation

    • humans are endotherms, such that when we get hot, we generate sweat
    • need of shelter
  • Fluid Regulation

    • cells in our body/cells prefer isotonicity for fluids inside our body
      • isotonic: solution having the same osmotic pressure as some other solution
      • hypertonic: solution having the lower osmotic pressure as some other solution
      • hypotonic: solution having the higher osmotic pressure as some other solution
      • e.g. after eating a salty meal, we need to “neutralized” the extra salt


  • Food Regulation

    • ghrelin: hormone synthesized and secreted by cells of stomach, and it is critical in serving us the feeling of hunger
      • synthesized ghrelin -> ghrelin gets secreted by cells of stomach -> ghrelin activates neurons in the brainstem -> synapses onto neurons in hypothalamus -> increase the synthesis of molecules associated with the feeling of hunger
      • why people feel like they need more food than another
    • leptin: hormone synthesized and secreted by white adipose tissue of the body, associated with the feeling of fullness/satiety
      • cells of white adipose tissue synthesize and secrete leptin -> gets circulated and binds to leptin receptor of neurons in the brainstem -> perception of satiety
      • why, after eating some food, you feel full/satiated

Self-Determination Theory of Motivation

This theory suggests that people are able to become self-determined when their needs for competence, connection, and autonomy are fulfilled.

  • e.g. students want to get a degree for university are self-determined
  • and that with the ability of being self-determined, we could jump from basic needs to self-fulfillment needs

Consider the following experiment:

  • participants were asked to play a game, in which they could either play it with:
    • continuously choosing the picture they chose at the beginning of the game (self-determined)
    • continuously choosing the picture they were told to choose
  • results show that when a choice is self-determined, we tend to perform better


  • in fact, if a choice is self-determined, we are more resilient to failure

  • the biological reason behind this is

    • VTA is well known for decision making, but not for motivation


    • data shows that:


      where if means:

      • during unsuccessful trials, the activity of VTA were higher for self-determined choice

      • if we have the autonomy to choose, areas of our brain implicated for decision making may be more resilient to failure

Week 12 | Social, Personality, and Cultural Psychology

Social Psychology

Social Psychology: the scientific study of the feelings, thoughts, and behaviors of individuals in social situations.

Some questions asked and answered by social psychology:

  • Why do we think we’re more unique than other people?
  • Can we make someone attracted to us?

Stanford Prison Experiment

The aim of this experiment was to investigate:

  • Why might people assigned to play the role of guards abuse those who are assigned to be prisoners?



  1. Healthy, male participants were recruited to participate in a 2-week prison simulation
  2. Randomly assigned to the role of prisoner or prison guard
  3. Prison guards were provided wood batons and mirrored sunglasses to prevent eye contact. Prisoners were fingerprinted, photographed, strip searched and given a prisoner number.

Remember, the participants are all undergraduates of Stanford University.


  • Study ended after 6 days due to psychological impact of the situation on participants
    • Prisoners became depressed and showed signs of trauma, launched a rebellion on the second day
    • Prison guards began to use force and harass prisoners, took away beds, toilet privileges, put some in solitary confinement

Hints at people changing behavior due to situation contexts.

Later, this study has been criticized for ”methodology”:

  • Possible fraud: Zimbardo (main researcher) asked guards to exert control over prisoners, instead of letting them decide what to do
  • Demand characteristics: participants change behavior to fit their interpretation of experiment

The Milgram Experiments

This comes from the idea that:

  • justification given for acts of genocide was that of obedience: soldiers said they were just following orders

The the central idea of this experiment is:

How far will people go in obeying an instruction if it involved harming another person?



  1. Healthy, male participants were recruited through newspaper ads for a study at Yale University
    • this time, no college students were used
  2. Participants were paired with another person and drew lots so one would be assigned the ‘learner’ and the other ‘teacher’
  3. Participant was always selected to be the teacher, and learner was a confederate (person that is part of the research team pretending to be a participant)
  4. Told to give the learner an electric shock each time he made a mistake, increasing the shock level each time

Milgram Study Results:

  • 65% of participants administered shock up to 450 volts, 100% administered shocks up to 300 volts


    • All participants stopped the study at least once, but were urged to continue by the experimenter
    • Participants experienced visible distress during study, as well as long-term stress as a result of participation
      • unethical
      • Resulted in revision of ethical standards of psychological research

This means the follows:

  • people are likely to follow orders given by an authority figure (if they recognize their authority as morally right and/or legally based ), even to the extent of killing an innocent human being. Obedience to authority is ingrained in us all from the way we are brought up.
    • in fact, this is common in the context of family, school, and workplace.

The Asch Experiments

The goal:

  • investigate the extent to which social pressure from a majority group could affect a person to conform.



  • Over the 12 critical trials, about 75% of participants conformed at least once, and 25% of participants never conformed.

Phenomenon’s in this experiment:

  • conformity:
    • changing one’s behavior or beliefs in response to explicit or implicit pressure (real or imagined) from others.
  • informational social influence:
    • the influence of other people that results from taking their comments or actions as a source of information about what is correct, proper, or effective.
  • normative social influence:
    • the influence of other people that comes from the desire to avoid their disapproval, harsh judgments, and other social sanctions (e.g. ostracism).

The take-away message is:

  • Why did the participants conform so readily? When they were interviewed after the experiment, most of them said that they did not really believe their conforming answers, but had gone along with the group for fear of being ridiculed or thought “peculiar”.
    • A few of them said that they really did believe the group’s answers were correct.
  • Apparently, people conform for two main reasons:
    • because they want to fit in with the group (normative influence)
    • because they believe the group is better informed than they are (informational influence).

Factors that impact conformity

  • Group size: conformity increases as group size increases

    • in this experiment, up to about 7 people opposing


  • Group unanimity: even if one person is with you instead of the group, result changes greatly
    • When all group members reported the wrong number, participants conformed ~30% of the time.
    • When even one other person dissented from the majority (agrees with you), the participant conformed only 5% of the time!
  • Expertise and Status: When we assume others are experts or if they are higher status than we are, we tend to conform more.
  • Culture: countries that are more interdependent (more on that next class!) have higher rates of conformity.
  • Anonymity: responding anonymously significantly reduces conformity

Bystander Effect

Consider the murder of Kitty Genovese

  • 28-year-old Kitty Genovese was stabbed outside the apartment building across the street from where she lived
  • 37 people witnessed the murder, but no-one called the police
    • reported by the news at that time, but in fact, there is no evidence on this

The smoke filled room experiment

  • Columbia students were placed in a room to complete questionnaire while waiting for experimenter- either alone, with 2 strangers, or 3 strangers
  • Smoke pumped into the room through a wall vent to simulate an emergency
  • When alone, noticed smoke immediately (~5 sec)
  • Students in groups took longer (~20 sec) and acted accordingly (evacuate)

The take-away messages here are:

  • Bystander Effect:
    • People are less likely to offer help to someone in distress if other people are also present.
  • Pluralistic ignorance:
    • if others are not doing anything, you will tend to think that nothing needs to be done
  • Diffusion of responsibility:
    • a reduction in a sense of urgency to help someone involved in an emergency or dangerous situation under the assumption that others who are also observing the situation will help.

But when is it more likely for someone to offer help?

Good Samaritan Study


  • A major cause of offering to help another person is whether one is in a hurry or not.

Research Method:

  1. Participants were chosen who were expected to be helpful (seminary students). They were primed to think about helping by being asked to prepare a talk on the Good Samaritan.
  2. Some of those participants were told that they were in a rush (were told that they were already late to give their talk and should hurry), others were told that they had plenty of time.
  3. Participants then passed by a “victim” in obvious need of help (a confederate).


Again, the take away message is:

  • the situation context will greatly influence people’s behavior

Factors that impact helping behavior

  • Notice that something is going on
  • Interpret the situation as being an emergency
  • Degree of responsibility felt
  • Form of assistance
  • Implementing the action choice

Fundamental Attribution Error

Why do we think we’re more unique than other people?

Fundamental Attribution Error:

  • the tendency for people to over-emphasize dispositional, or personality-based explanations for behaviors observed in others while under-emphasizing situational explanations.

  • e.g.


    • I am speeding because I need to go to the hospital quickly
    • others will just think that I am a jerk

Fundamental Attribution Error (FAE) Study


  • Even when people have information about the situational causes of another person’s behavior, they will make dispositional inferences.

Research Method:

  1. Participants read an essay about Castro’s Communist regime in Cuba that had been written by a fellow undergraduate.
  2. Half of the participants read a pro-Castro essay, and half of the participants read an anti-Castro essay.
  3. Half of the participants were told that the person writing essay had been directed to write how they felt, the other half were told that the writers had been assigned a pro- or anti-Castro stance by the experimenter.
    • dispositional: writers wrote on how they felt
    • situational: writes were assigned the essay


  • Participants inferred the essayist’s attitude based on the opinions expressed in the essayeven though they knew that their position had been assigned!


The Spotlight Effect

The idea is:

  • People will overestimate the extent to which their actions and appearance are noticed by other people

Related Experiment:

  • People were asked to wear some embarrassing T-shirt, and then talk to someone else.
  • In the end, compare the person’s estimate and the actual result, whether if the other person noticed the T-shirt

Research Method:

  1. Three groups of participants: Targets, Observers, Controls
  2. Participants in the Target condition were told to put on an embarrassing t-shirt and to interact with another group of participants (the Observers).
    • Control condition watched videos of the procedure.
  3. Targets were asked to estimate the percentage of observers that they thought noticed their embarrassing shirt



  • We overestimate to the extend our action/appearance being noticed

Ask a question

  • Doesn’t it depend on people’s perception/cultural backgrouds?
    • Some people might be accustomed to seeing those things, hence did not notice
    • Some people might just think this is a normal shirt

Biological Related Explanation:

  • It turns out that part of our brain that deals with emotion also dealt with non-real events
    • if you are experiencing embarrassment (emotion), you might experience/perceive false information/events such as people noticed your T-shirt (non-real events)

Related to the false consensus/false uniqueness effect!

  • false uniqueness
    • underestimate the extent to which other people share the same positive attitudes and behaviors.
  • false consensus
    • that their personal qualities, characteristics, beliefs, and actions are relatively widespread through the general population.

Week 13

Social Psychology (Continued)

Theories of Emotion

Can we make someone feel happy/sad, or even feel attracted by us?

To find out, we need to study how our emotion arises:

  • Early Theories of Emotion: James-Lange

    • emotion is based on a physical arousal, hence is dependent on how you interpret the physiologically response

    • a stimulus -> autonomic arousal -> interpolates to an emotion

    • e.g. a bear -> body shaking -> means I should be afraid -> afraid


  • Cannon-Bard Theory of Emotion

    • your response and your emotion should be simultaneous. It cannot be that one caused the other

    • there should be a central control signal: cerebral cortex that sends information to both

    • e.g.


  • Schacter-Singer Two Factor Theory of Emotion

    • combination of both

    • a stimulus still leads to autonomic arousal first, but your emotion is dependent on your appraisal/cognitive label

    • e.g. if you have labelled a particular response+stimulus as being “scary”, then you are scared, and vice versa.


The Shaky Bridge Study

Research question: can people misattribute the cause of their autonomic/physiological arousal?

  • e.g. in this experiment, participants are “tricked” into thinking their heart rate went up because of the female (rather than the bridge). As a result, feel “attracted” to the female.


  1. Male participants were stopped by an attractive female confederate after crossing a sturdy or shaky bridge (in other replications- immediately after crossing the shaky bridge, or after they had time to get HR back at rest)
  2. The female confederate (blind to the study hypothesis) asked if they would be interested in participating in a study, provided her phone number if they have any further questions about the project



  • Male participants misattributed the response and stimulus pair, and therefore had a different “label”:



  • Individuals mistake the cause of their arousal, and hence trick their emotion

Social Identity Experiment

Where are you really from? (Cheryan & Monin, 2005)

  • the idea is: if your social identity is under threat, then your response might change



  • left: when Asian Americans where under identity denial, they took more time to generate those films
  • right: when Asian Americans where under identity denial, they sought to generate more films
    • in general, when under social identity, you tend to spent more effort to prove your identity

Identity denial:

  • A type of social identity threat that occurs when an individual is not recognized as a member of a group to which he or she belongs

Social Identity Theory

  • Personal identity – e.g., “I worry a lot”
  • Social identity – e.g., “I am a student”
    • a person’s sense of who they are based on their group membership(s)
    • can have multiple social identities

Social identity is important because it can be used to explain intergroup behavior:

  • source of pride, self-esteem, and belonging.
  • divided the world into “them” and “us” based through a process of social categorization


Revision on schema:

  • schemas allow us to fill in missing information based on theories/schemas we have already
  • also helps us to save energy when thinking about things, as well as easier memory encoding

However, remember that schemas can change/are shaped by:

  • Experiences with social environment

Then, we can define Stereotype - mental representation of a social group and its members

  • i.e., a type of schema

Similar, related to stereotype are attitudes - evaluations people make about objects, ideas, events, or other people’s beliefs, feelings, predispositions to act in a certain way

  • i.e. a more evaluative schema (e.g. is X good or bad?)
  • attitudes are accessible if they are easily retrieved from memory
    • Higher accessibility $\to$ stronger influence on behavior
  • Explicit attitudes:
    • Conscious beliefs that can guide decisions and behavior
  • Implicit attitudes:
    • Unconscious beliefs that can still influence decisions and behavior


Prejudice is an antipathy based on faulty and inflexible generalization. It may be:

  • felt or expressed.
  • directed toward a group as a whole,
  • or toward an individual because he is a member of that group.

Prejudice is an attitude

Q: What makes talking about race difficult?


Not about physical color blindness, but:

  • The idea that racial and ethnic group categories do not matter; we all have a superordinate identity and everyone should be judged as individuals equally


This attempts to:

  • Ignoring and avoiding discussion of group categories altogether

However, study results show that:

  • not all Americans agree with the statement of color-blindness



    • horizontal bar means the percentage of people that agreed to the above statement, that all Americans are treated equally
Color-Blindness as a Strategy to Avoid Race Discussion

The idea is simple: if I do not notice race, then I cannot be racist.

However, it turns out to not work, because racial categories are processed automatically


  • measure event related brain potential (ERP) of a participant while looking at pictures of people with different race
    • ERP is like a brain’s electrophysiological response to a specific stimulus/event


  • Our brain categorizes races automatically


This means we can only be appearing to be color-blind

Appearing Color-Blind

Even if people think they are color-blind:

  • when black partner was present, people tend to not ask about race


In other words,


  • the greater people think they are colorblind, the more likely they are to avoid race questions



  • for example, the stronger you want to avoid race questions, e.g. in order to avoid disapproval from others, the more likely it is to actually avoid bringing up race

Colorblind Strategy is Learned

This talks about the fact that:

  • we attempts to be color-blind because we are learnt to do so


  • Two groups of children
  • Ask them to categorize people by letting them ask questions about them
  • tasks involve
    • categorization not involving race
    • categorization that will involve race




  • for 8-9 year-old, they did not care much about race
  • for 10-11 year-old, they attempts to not mention race
    • as a result, did much worse for race-relevant categorization

Consequence of Appearing Colorblind

Psychological threat for majority

  • Challenges self-image of being a good person
  • Acknowledging role of privilege and potential contribution to others’ disadvantage
  • Challenges view of society as meritocratic

Psychological and interpersonal threat for minority

  • Means attending to racial injustices and microaggressions
  • Challenges view of society as meritocratic

In the end, it leads to Anxiety, defensiveness, anger in the world

Goal Mismatch and Ambiguous Social Cues

It turns out that different group of people tend to have different goals.

  • as a result, different group of people behaves differently

For example:


where, within a single conversation:

  • white people want to be liked more than respected by the others
  • black people want to be respected more than liked by the others

A common phenomena happens here:

  • A white person would want to smile more during a conversation (to be liked)
  • A black person would perceive that as not respecting him/her, hence feels offended
    • due to goal mismatch

Similarly, there are social cues that are ambiguous as well:


Factors Causing Ambiguity

  • Lack of attention
    • if you are not paying attention, then you might not be able to correctly determine the social cues. In turn, that might cause misunderstandings.
  • Distrust
    • distrust within a school, that you may think what you get from teachers/students are for bad intentions, because you distrust them

Mitigating Distrust:

  • Critical Feedback: I’m giving you these comments so that you’ll have feedback on your paper
  • Critical feedback & assurance: I’m giving you these comments because I have very high expectations and I know that you can reach them (trust from teacher)


Changing our Attitudes

Enos Train Study

Central Question:

  • How can we change our attitudes?


  • exclusionary political attitudes can be stimulated by very minor, non-invasive demographic change
    • i.e. demographic change could create inter-group conflicts


  • Regular commuters during the rush hours were measured at first, by their political attitudes and their demographics
    • mostly European/American
  • Two Spanish speaking confederate were “introduced” to the commuters, by asking them to speak Spanish (non-invasive)
    • causing a minor demographic change
  • After three days, regular commuters’ exclusionary attitudes are measured and compared
  • Again, after 10 days, the same is measured


  • null hypothesis: a type of hypothesis used in statistics that proposes that there is no difference between certain characteristics of a population



  • the 0.0 point is the null hypothesis
  • within a short period of time, minor, non-invasive change in demographic induces political exclusions
  • however, a prolonged contact reduces exclusionary attitudes

Intergroup Contact Theory


  • Under appropriate conditions, interpersonal contact is one of the most effective ways to reduce prejudice between groups
    • by Gordon Allport, writer for the nature of prejudice

Those appropriate conditions include:

  • Equal status
    • Members of the group should have similar backgrounds, qualities, and characteristics
  • Common goals
    • Both groups must work on a problem/task and share this as a common goal, sometimes called a superordinate goal
  • Intergroup cooperation
    • Groups need to work together in the pursuit of common goals
  • Support of authorities, law or customs
    • Both groups must acknowledge some authority that supports the contact and interactions between the groups
  • Personal interaction
    • The contact situation needs to involve informal, personal interaction with outgroup members

Personality Psychology

Personality psychology:

  • the distinctive pattern of thoughts, feelings and behaviors that vary among individuals and how they predict reactions to other people
    • how personality develops as well as how it influences the way we think and behave


  • image-20201203133414114

    where, the graph contains:

    • mean
    • standard error/error bars - standard deviation of its sampling distribution or an estimate of that standard deviation.

Personality Theories

The idea is that:

  • since testing personality is hard (e.g. testing intelligence), because it is subjective and may fluctuate in different situations
  • we need to find a way to test/measure things by eliminating as much variability as possible

Psychoanalytic Theory

  • emphasizes the unconscious determinants of behavior
  • the unconscious ID-EGO-SUPEREGO
    • the id is the set of uncoordinated instinctual desires
    • the super-ego plays the critical and moralizing role
    • the ego is the organized, realistic agent that mediates, between the instinctual desires of the id and the critical super-ego;


Trait Theory

Trait Theory

  • understand individuals by breaking down behavior patterns into observable traits
    • a way to study of human personality


Social Cognitive Theory

Social Cognitive Theory:

  • describes personality as a composite of an individual’s psychological processes
    • i.e. bringing in some social psychology into personality analysis

Marshmallow Test

  • Tests Delayed gratification:
    • the ability to wait for something you want
  • Research question:
    • When does delayed gratification develop in children?
    • What does the ability of delayed gratification mean for life?
  • Method:
    • offered a choice between one small reward provided immediately or two small rewards if they waited for a short period, approximately 15 minutes
    • the reward used was marshmallow
  • Result
    • Age predicted better delayed gratification
    • Children who waited longer for greater rewards tended to have better life outcomes and were more successful adults


  • 2018 replication found that achievement and parent-reported behavior changes were not observed when controlling for SES and mother’s education level
    • i.e. higher socioeconomic status -> better delayed gratification -> of course more successful

Regulatory Focus

This talks about the idea that:

  • Developed in response to the assertion that people approach pleasure and avoid pain
  • People have different motivational tendencies when it comes to goal setting

Especially, the different motivation of promotion and prevention



  • Can a change of context and environment change your disposition/motivation?


  • If strategic eagerness fits promotion and strategic vigilance fits prevention, then people in a promotion focus should prefer to pursue goals with an eager strategy and people in a prevention focus should prefer a vigilant strategy



  • then if a participant writes response about it, experimenters would have a feeling whether they are the vigilant guy, or the eager guy
  • then, they were asked to assign price to the mug





  • prevention focus $\Rightarrow$ think in a vigilant way $\Rightarrow$ value the object more accurately in a vigilant way

  • promotion focus $\Rightarrow$ think in a eager way $\Rightarrow$ value the object more accurately in a eager way

The better fit your thinking is with your personality $\Rightarrow$ the more value you will assign to it

Cultural Psychology

Culture is:

  • Unique system of information and social meaning shared by a group and socially transmitted across “generations”
  • Groups of people who operate within a shared context/exposed to similar ideas

Bear in mind that concept of culture itself is defined differently in different cultures/parts of the world

Culture tends to have the following aspects:

  • Objective elements
    • e.g. architecture, clothes, foods, art, tools (from utensils to FB/Twitter!), music, ads
  • Subjective elements
    • psychological processes, e.g., attitudes, values, beliefs, norms, behaviors, worldview
    • those are what being explored by psychologists

In fact, we can have:

  • countries having different cultures
  • cities having different cultures
  • campuses having different cultures


Caveats of studying culture

  • Boundaries of cultures are almost never clear-cut
  • Layers of cultures
  • Globalization
  • Cultures change over time
    • dynamic, not static (via ratchet effect)
    • Ratchet effect: cultural modifications and improvements stay in the population fairly readily (with relatively little loss or backward slippage)
  • Variability within cultures

Level of Universality in a Culture

Are psychological processes universal or culture specific (i.e., culture-bound)?

  • series of steps or mechanisms that occur in a regular way - not necessarily a deterministic one - to attain changes in behavior, emotion, or thought.

Psychological processes can be universal in some ways, but not in others

  • Existence – Does the process exist in some form in all cultures?
  • Function – Is the process used in the same way in all cultures?
  • Accessibility/Frequency – Do different cultures rely on/use the process more or less than others?

Culture Influencing Individual

  • Cognitive representation of who one is – the ideas or images one has about oneself and how/why one behaves
  • Sense of self consciously & unconsciously shapes thoughts, actions, and feelings


Builds to the Self-Construal Theory: Two views of self




  • the boundary for ingroup is more permeable for independent self
  • the boundary for individual is more permeable for interdependent self

Culture Difference of Self-Description in 20 statements

  • culture influences individual/self


In the end, it turns out that we have a mutual constitution of culture and psyche:

  • our self-conceptions are shaped by cultural practices
  • culture is shaped by member’s self-concept



However, there is still the possibility that:

  • One individual can hold both independent and interdependent ideas of self

Week 14

New Chapter

Psychology Disorders


Before we talk about psychology disorders, we need to talk about stress.

  • Stress: the nonspecific responses of body compromising one’s ability to adapt to the posed threat
    • e.g. eat more/less undergo stress
    • e.g. sleep less undergo stress

Consider the hippocampus area of two monkeys, one under stress and one not.



  • we see a microscopic slide of the hippocampus area
    • remember, hippocampus is part of the limbus system, and also part of the LTM encoding
  • the black dots are the cell body areas (grey matter)
    • more black dots in the middle if not under stress

In particular, if we look closer at the above picture:



  • monkey under stress has sparse neurons
  • monkey under stress has reduced number of nuclei of neurons (very black dots) in the hippocampus
  • monkey under stress atrophied dendritic branches
    • decreased synaptic efficacy/communication
  • monkey under stress reduced synapses
    • decreased synaptic communication

However, stress is associated with

  • The activation of the pathway in the hypothalamic pituitary adrenal (HPA) axis, which may lead to inflammatory responses
    • this pathway is also related to causing trauma

HPA Axis

Hypothalamic pituitary adrenal (HPA) axis:

  1. Neurons of the hypothalamus (subcortical) receives, and monitors, one’s information in the environment

    • recall that thalamus was responsible for receiving/forwarding sensory information
    • hypothalamus part of the limbic system, hence related to emotional processing
  2. If hypothalamus is activated due to stress from one’s environment, the corticotrophin releasing hormone (CRH) is secreted/released from neurons of hypothalamus

  3. Then, those CRH then binds to receptors to activate neurons in the pituitary gland

  4. After that, neurons in pituitary gland secrete/release adrenocorticotrophic hormone (ACTH)

    • pituitary gland is part of the brain, and it is called a “gland” because it releases hormone


  5. Those ACTH then circulates in bloodstream and bind to receptors in the cells of adrenal glands, so that those cells release glucocorticoid hormones (GC)

    • for instance, Cortisol is an example of glucocorticoid hormones
  6. The GC then circulates in the bloodstream and bind to receptors to receptors of potentially every biological cell, as long as that cell has a mineralocorticoid receptor (MR) or a glucocorticoid receptor (GR)

  7. The binding of GC to GR or MR will enhance transcription of genes that produce inflammatory processes

    • as a result, too much inflammation will kill many cells in your body
    • therefore, since it depends on your own gene, the response you have for stress may be different than others


  • The binding affinity of GC hormones are higher for MR than for GR in cells.

As a result, it means:

  • binding to the glucocorticoid receptor (GR) will enhance the transcription of genes that produce inflammatory processes
    • because, by default, those hormones are not binding to GR, and you should not be killing your cells
    • as a result, those inflammatory responses are caused by chronical activation of the pathway, hence binding to GR
    • so chronic stress is bad

General Adaptation Syndrome

In general, a moderate level of stress -> increase adaptation functioning/resilience -> good

  • however, chronic stress will reduce adaptation functioning



  • alarm stage -> beginning of HPA axis
    • for example, alarm stage would be the stress you have when you got a pop quiz
  • resistance stage -> GC hormone binding to mostly mineralocorticoid receptor MR + little GR of your body cells
    • of course, the binding affinity also depend on the number of receptors/cells you have in your body. The less there is, the less resistance you have/more probable that GR will be bonded
  • exhaustion stage -> activation of glucocorticoid receptors GR of cells
    • causing both physical and mental exhaustion


  • this would be more like a long term trend for stress
  • short term stress would be related to sympathetic autonomic system

Trauma and Resilience

Level 1 trauma center

  • highest level of surgical care to trauma patients

Resilience is defined as:

  • stable trajectory to healthy functioning
    • data suggest that if you had a traumatic event, then the first symptom of post-trauma would appear within 0-7 years
    • so you need to have a stable trajectory over 7 years to be okay
  • assessment of resiliency would then use emotional scales, ratings on level of coping and confidence…


  • longitudinal study of psychological functioning of patient after a single traumatic stressor, and admittance to level 1 trauma center


  1. Presence of “human intention” during the traumatic stressor, this is associated with a lower of resiliency
    • e.g. being beaten
  2. Underestimating or overestimating the difficulty of coping immediately after the traumatic stressor, this is associated with a lower level of resiliency
  3. Higher anger and depressive level before the traumatic stressor, this is associated with lower level of resiliency
  4. Increased education level indicated higher level of resiliency

What is Psychological Disorder

To be a psychological disorder, we need to have:

  • a set of abnormal cognitive symptoms and
  • a set of abnormal behavior symptoms
  • so that it causes/potentially causes impairment in social, occupational, or other areas of functioning of oneself and/or others
    • for example, homosexuality would not impair oneself and/or others, so it should not be a disorder

In fact, the validated criteria for classification of psychological disorder is only done in 1950’s, by the book called “American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM)

  • current version is DSM-5
  • but the DSM is heavily relied upon by clinicians, researchers, and etc.

While the DSM is very powerful, it has some significant limitations:

  • absence/inference of biomarkers
    • many symptoms described on the book is subjective/inferred, namely, a physical description by a clinician on the patient or by the patient himself/herself
      • e.g. biomarkers would be understanding things from your blood sample, brain images, etc
      • e.g. non-biomarkers would just be descriptions of symptoms

Final Quick References

  • Hypothalamus
    • sends signals to
      • control hormone release in gonad -> sex
      • HPA Axis
        • starts with Hypothalamus releasing corticotropin-releasing hormone
        • activates receptors in pituitary gland, and releases adrenocorticotrophic hormone
        • activates receptors in adrenal gland, and releases glucocorticoid hormone
        • binds to every biological cells that have mineralocorticoid receptor/glucocorticoid receptor
          • binding of GC to GR is bad -> inflammation
    • get signals from
      • ghrelin from stomach/pancreas -> hunger
  • Hippocampus
    • sends signal to
      • memory and cognition
      • indicate stress
        • reduced cell body areas
        • atrophied dendritic branches
        • impairment of memory and cognition ability
  • Frontal Lobe
    • sends signal to
      • control overall emotions
        • e.g. signals to amygdala for panic
      • low level of neurotransmitter -> low brain wave frequency -> depression
      • irregularities of neuro circuits -> related to antisocial personality disorder
        • also related to depression
  • amygdala
    • sends signal to
      • control negative emotion, such as fear
      • controls panic
      • smaller amygdala -> related to antisocial personality disorder
  • insula
    • sends signal to
      • receives somatosensory inputs and control emotions such as anger, guilt
  • Medial pre-frontal cortex
    • sends signal to
      • more active for ingroup members
      • controls information related to self/one’s self/self-schema
  • Overall Brain
    • larger ventricles -> schizophrenia
    • abnormal gene mutations
      • -> schizophrenia
      • -> autism
    • reduction in volume of many regions in brain
      • -> Attention Deficit/Hyperactivity disorder

CBT Good for

  • Anxiety Disorders
  • OCD
  • Depressive Disorders
  • Adolescent Depressive Disorders
  • (Dialectical Behavior Therapy) Borderline Personality Disorder
  • (Applied Behavioral Analysis) Autism
    • very costly and time consuming because it is hard

Antidepressants (SSRIs) Good for

  • OCD
  • Depressive Disorders
  • Adolescent Depressive Disorders

Atypical Antipsychotics Good for

  • +mood stabilizer lithium: Bipolar Disorder
  • Schizophrenia