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LECTURE 1-2: HISTORY OF COGNITIVE PSYCHOLOGY

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What is psychology?

The study of mental processes and behaviour

What is cognitive psychology?

The study of mental processes such as perception, attention, memory, problem solving, and decision making

Fundamental challenge of cognitive psychology?

Mental processes are subjective and can't be directly observed by others (the "black box")

How did philosophy approach the mind?

Using logic, reasoning, and reflection to speculate about what's in the box

What was Donders' key idea (1868)?

If thought takes time, we can measure reaction times to infer how long a mental process takes

What is reaction time?

How long it takes to respond to a stimulus, usually in milliseconds

What is the subtractive method?

Compare two tasks that differ by one extra mental process. The difference in RT estimates the time that process takes.

What is mental chronometry?

Using reaction times to infer mental processes

What did Donders find by subtracting simple RT from choice RT?

A decision takes about a tenth of a second

Why is Donders important?

First objective cognitive experiment. Showed controlled experiments can infer mental processes from observable measures.

Who set up the first experimental psychology lab, where and when?

Wundt, Leipzig, 1879

What is structuralism?

Wundt's approach: overall experience is built by combining basic elements of experience called sensations

What is analytic introspection?

Participants intensively trained to report their conscious experience

Four weaknesses of introspection?

Highly variable, subjective and hard to verify, limited to conscious awareness, hard to replicate

Two strengths of introspection?

Contributed to cognitive theories and encouraged development of new methods

What is functionalism and who proposed it?

William James. Asks what consciousness is FOR, understanding mental processes by their adaptive function.

Structuralism vs functionalism?

Structuralism: what are the basic elements of consciousness? Functionalism: what is consciousness for?

What did behaviourism focus on, and why?

Observable, measurable behaviour, because researchers wanted psychology to be an objective science

Who bridged behaviourism and cognition?

Tolman (1930), with rats in mazes

What is latent learning?

Learning that occurs without reward and only shows once a reward is introduced

What did Tolman conclude rats formed?

A cognitive map of the maze while exploring without reward

What was the cognitive revolution?

The mid-20th-century shift in psychology's focus from behaviourism to cognition

Skinner's view of language (1957)?

Acquired through learning mechanisms, especially reinforcement

Chomsky's view of language (1959)?

Children are born with a Language Acquisition Device that lets them learn language using universal grammar

What is universal grammar?

Innate constraints on possible grammar in all human languages

How did WWII contribute to the cognitive revolution?

Radar operators raised interest in vigilance, fatigue, and attention. Codebreaking raised interest in reasoning. Targeting raised interest in motion perception and decisions.

How did computers contribute to the cognitive revolution?

Gave a new metaphor for the mind: the information processing approach

What is the information processing approach?

Thinking involves a sequence of internal cognitive operations, studied by building models, testing predictions, and comparing humans and computers

LECTURE 2-3: PSYCHOPHYSICS AND SIGNAL DETECTION

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What is psychophysics?

The study of the relationship between physical properties of stimuli and psychological experience

Who aimed to quantify sensation?

Gustav Fechner

What is an absolute (detection) threshold?

The stimulus intensity detected a certain percentage of the time, e.g., 50%

Are thresholds fixed?

No, they vary across trials and can be changed by factors like attention

Relationship between sensitivity and threshold?

Higher sensitivity means a lower threshold

What is a difference threshold (JND)?

The smallest change in a stimulus that can be detected a certain percentage of the time

What is Weber's law?

The JND depends on the proportion of the original stimulus, not the absolute difference. Bigger stimulus, bigger JND.

Real-world example of Weber's law?

Shrinkflation: companies shrink products by amounts too small to notice

Three classic psychophysical methods?

Method of limits, method of adjustment, method of constant stimuli

Method of limits?

Change the stimulus in steps using alternating ascending and descending staircases. Threshold = average of crossover points.

Descending vs ascending staircase?

Descending starts clearly detectable and decreases. Ascending starts undetectable and increases.

Method of adjustment?

Participant adjusts the stimulus until it's barely detectable or matches a reference stimulus

What is the point of subjective equality?

The point where an adjusted stimulus seems the same as the reference stimulus

Method of constant stimuli?

Stimulus levels presented in random order. Allows full sampling of the psychometric function.

Strength and weakness of method of limits?

Fast, but anticipation bias

Strength and weakness of method of adjustment?

Easy, but least reliable

Strength and weakness of method of constant stimuli?

Most accurate, but slow

How do researchers choose a method?

Trade-off between speed and precision

What did the peripheral cue study show?

When attention was directed by a peripheral cue, the test stimulus didn't need to be as bright to be detected. Attention changes thresholds.

What is covert attention?

Attending to something without looking directly at it

Where did signal detection theory (SDT) originate?

WWII radar operators deciding whether blips were aircraft or noise

What two things does SDT separate?

Sensitivity (d') and response bias/criterion (c or beta)

Four outcomes in the SDT matrix?

Hit (signal present, said yes), miss (present, said no), false alarm (absent, said yes), correct rejection (absent, said no)

Why is the signal described as "noisy evidence"?

The same stimulus doesn't produce exactly the same neural response every time

What is the noise distribution?

Signal-like internal activity even when no signal is present, e.g., neurons firing in darkness

What is d' (d prime)?

Sensitivity: the distance between the peaks of the noise and signal+noise distributions. Bigger gap, easier to distinguish.

What is the criterion (c or beta)?

The point on the internal response dimension where the observer decides to say "yes"

Effect of a liberal criterion?

High hit rate but high false alarm rate

Effect of a strict/conservative criterion?

Low false alarms but fewer hits

Does changing the criterion change sensitivity?

No. It only shifts the trade-off between hits and false alarms.

What does an ROC curve plot?

Hit rate against false alarm rate across different criteria

What does area under the ROC curve show?

Sensitivity. Larger area means better discrimination.

What does position along an ROC curve show?

The criterion. Lower on the curve is strict, higher is liberal.

What does training do to the signal distribution?

Narrows the internal responses, making detection easier

LECTURE 4: PERCEPTION

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Sensation vs perception?

Sensation is detecting physical energy. Perception is organising and interpreting it into experience.

Examples of sensation?

Retina responds to light, cochlea to sound waves, skin to pressure and temperature, taste buds and olfactory epithelium to chemicals

Bottom-up processing?

Perception built from sensory information toward meaning, driven by stimulus properties

Top-down processing?

Using prior knowledge, expectations, and context to interpret sensory input

Gibson's direct/ecological theory (1950): four claims?

The environment contains enough information. Perception guides behaviour. Perception is direct, without cognitive inference. Our systems evolved to detect this information.

Is Gibson's theory bottom-up or top-down?

Bottom-up

What are invariants?

Stable relationships in the environment that stay constant as we move, allowing direct perception

Four sources of information Gibson described?

Optic flow, motion parallax, texture gradients, affordances

What is optic flow?

The pattern of movement across the retina caused by self-motion. Gives direction, speed, and distance.

What is motion parallax?

Nearer objects move faster across the retina than distant ones, giving depth

What is a texture gradient?

Evenly spaced elements look more tightly packed with distance

What is an affordance?

An action possibility an object or environment offers, depending on its features and the organism's abilities

Do affordances exist if nobody perceives them?

Yes, according to Gibson. Later work focused on perceived affordances.

What is the visual cliff study (Gibson & Walk)?

Infants placed on glass over an apparent drop mostly avoided the deep side. Concluded depth perception doesn't require learning.

Crawling experience critique of the visual cliff?

35% of inexperienced crawlers avoided the cliff vs 65% of experienced crawlers (Bertenthal et al., 1984)

Kitten critique of the visual cliff?

Kittens raised in the dark for 27 days didn't avoid the cliff, but did after 6 days of light

Social context critique of the visual cliff?

12-month-olds crossed the deep side more if mothers smiled, and avoided it if mothers looked frightened

What do the visual cliff critiques suggest?

Depth perception involves experience and context, not just innate ability

Example of top-down processing in vision?

An ambiguous blob is identified differently depending on surrounding context

Example of top-down processing in hearing?

Phonemic restoration (Warren, 1970): the cough-covered "*eel" is heard as wheel, heel, peel, or meal

Overall view of perception?

An active construction of reality combining bottom-up and top-down processes

LECTURE 5: PERCEPTION PART 2

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What did Gestalt psychologists argue?

Perception is more than combining sensations. We organise input into meaningful wholes.

Are Gestalt principles descriptive or explanatory?

Descriptive. They say what happens, not the mechanism.

Principle of Pragnanz?

We organise input into the simplest, most stable, regular, symmetrical form

Figure-ground segregation?

Separating an object (figure) from its background (ground)

Principle of proximity?

Objects near each other are grouped

Principle of similarity?

Similar elements are grouped

Principle of continuity?

Elements along a smooth path are seen as one object

Principle of closure?

Incomplete objects are perceived as whole

"FoRiNsTaNcE" example?

Similarity (matching case) conflicts with proximity (letters in words), making it hard to read

Four limitations of Gestalt principles?

Descriptive not explanatory. Limited account of top-down influences. Limited account of individual differences and expertise. Unclear which principle wins when they conflict.

What regularity-based expectation shapes shading perception?

Light comes from above

Kitchen context study?

After seeing a kitchen scene, people identified a briefly flashed loaf of bread better than objects that didn't fit the context

Six challenges for object recognition?

Viewpoint, size/distance, lighting, occlusion, background, within-category variation