IGCSE Psychology: Cognition and Behaviour — Revision Notes

Condensed for the final weeks. For the full explanation, use the Cognition and Behaviour study guide.

Memory

Encoding → storage → retrieval.

Multi-store model: sensory register (very brief, large capacity) → attention → short-term memory (5–9 items, 18–30 seconds) → rehearsal → long-term memory (potentially unlimited).

Long-term memory types: episodic (events), semantic (facts), procedural (skills).

Evaluation: supported by the primacy–recency effect (Murdock’s serial position curve study: words from the start and end of a list are recalled far more reliably than words from the middle) and by brain-damage case studies, but too simple — it treats each store as unitary, and rehearsal alone cannot explain why emotionally significant events are remembered without any rehearsal.

Working memory model: replaces the single short-term store with four active components — central executive (limited-capacity attention controller), phonological loop (brief acoustic storage of spoken/written material), visuo-spatial sketchpad (visual and spatial information) and episodic buffer (integrates the other components and links to long-term memory). Baddeley and Hitch investigated the model with dual-processing tasks: two tasks drawing on the same component (e.g. two visual tasks) disrupted performance far more than tasks drawing on different components (e.g. one visual, one verbal) — evidence STM is not a single store.

Forgetting:

• Interference — proactive (old disrupts new) and retroactive (new disrupts old).
• Retrieval failure — the information is stored but the cue needed to access it is missing. This is why a memory can return later with the right prompt, which pure decay cannot explain.

Bartlett’s reconstructive memory: recall is an active reconstruction shaped by schemas and by ‘effort after meaning’ — filling gaps and ironing out unfamiliar details so the memory makes sense — not a replay. In War of the Ghosts, unfamiliar cultural details were omitted, the story was shortened, and elements were changed to fit participants’ own expectations — the basis of the case against eyewitness reliability. Factors affecting the accuracy of memory: interference, context and false memories (confident but inaccurate recollections created by misleading information or suggestion after the event).

Implication for eyewitness testimony: because recall is reconstructive, a witness’s account can be altered by leading questions and by information encountered after the event, without the witness being aware of any change. This is why police interviews should use open, non-leading questions, and why witnesses should be interviewed separately and as promptly as possible — before their memories can be influenced by each other or by media coverage.

Perception

Sensation is the raw sensory data; perception is the brain’s interpretation of it.

Depth cues: monocular — height in plane, relative size, occlusion, linear perspective; binocular — retinal disparity, convergence.

Factors affecting perception: expectation, motivation, emotion and culture. Named studies: Gilchrist and Nesberg (hungrier participants rated food images as brighter — motivation); Bruner and Minturn (an ambiguous figure read as “B” or “13” depending on the surrounding sequence — context/expectation); Kunst-Wilson and Zajonc (participants preferred shapes they had been shown too briefly to recognise — emotion); Nisbett and Miyamoto (cultural differences in eye movements and scene recall — culture).

Illusions are useful because they reveal how perception works, via four explanations: ambiguity, misinterpreted depth cues, fiction and size constancy. The Ponzo and Müller-Lyer illusions arise from misinterpreted depth cues, Rubin’s vase from ambiguity, the Kanizsa triangle from fiction — the brain supplying edges that do not exist — the Necker cube from ambiguity too, since it flips unpredictably between two equally valid 3D interpretations, and the Ames Room from size constancy — a distorted trapezoidal room disguised to look rectangular, so the brain keeps applying its normal assumption that retinal size indicates distance, making two equal-height people in different corners look drastically different in size. Together these show perception is an active hypothesis the brain forms and revises, not a passive reading of the image.

Two competing explanations:

• Gibson — direct, bottom-up. The sensory information is sufficient in itself. Explains accurate everyday perception; cannot explain illusions.
• Gregory — constructivist, top-down. The brain infers from expectation and experience. Explains illusions; struggles to explain the speed and general accuracy of perception.

Biopsychology

Nervous system: central (brain, spinal cord) and peripheral (somatic — voluntary; autonomic — involuntary control of internal organs).

Endocrine system: glands release hormones into the bloodstream. Autonomic nervous system triggers fight or flight (adrenaline). James-Lange theory of emotion: bodily arousal comes first, emotion is our interpretation of it.

Neurons: sensory (receptors → CNS), relay (within CNS), motor (CNS → muscles/glands). Synaptic transmission: neurotransmitters released, cross the gap, bind to receptors causing excitation or inhibition; then reuptake. Hebb’s theory of learning and neuronal growth: neurons that fire together repeatedly strengthen their connection.

Brain lobes: frontal, temporal, parietal, occipital, plus the cerebellum. Localisation of function: motor, somatosensory, visual, auditory and language areas — Broca’s area (speech production) and Wernicke’s area (language comprehension). Penfield’s study of the interpretive cortex: electrical stimulation of the temporal lobes during surgery triggered vivid memories and sensations.

Scanning techniques: CT (structure, X-ray), PET (metabolic activity via tracer), fMRI (blood-oxygen changes). Tulving’s ‘gold’ memory study: PET scans showed episodic and semantic memory are processed in different brain regions.

Neurological damage (stroke, injury) can affect motor abilities and behaviour depending on the area damaged.

Research methods

Method	Strength	Weakness
Laboratory experiment	High control, cause established	Artificial, low ecological validity
Field experiment	More realistic	Less control over variables
Observation	Natural behaviour	No control, observer bias
Questionnaire	Large samples, quick	Social desirability bias, low validity
Interview	Detailed, flexible	Time-consuming, interviewer effect
Case study	Rich detail on rare cases	Not generalisable

• Independent variable — what is changed. Dependent variable — what is measured. Extraneous variables must be controlled.
• Hypothesis — a testable prediction. The null hypothesis predicts no effect.
• Reliability — consistency. Validity — accuracy of what is measured.
• Sampling: random, opportunity, systematic, stratified. Opportunity sampling is quick but unrepresentative.

Ethics must follow BPS guidelines: informed consent, protection from harm, right to withdraw, confidentiality, debriefing. Deception is not an outright ban — it is justified where scientifically necessary, provided participants are debriefed and can withdraw their data; several landmark studies (e.g. Milgram, Asch) deceived participants and were still considered ethically defensible once debriefed. Deception is an issue to be managed, not banned.

Repeated measures designs (the same participants complete every condition) risk order effects — practice may improve performance in whichever condition comes second, or fatigue and boredom may worsen it — and demand characteristics, since completing several conditions makes it easier for a participant to guess the aim and change their behaviour accordingly. Both are addressed by counterbalancing, where the order of conditions is varied systematically across participants (half do condition A first, half do condition B first), and by using different but equivalent materials in each condition so practice on the actual content cannot occur.

Exam traps

• Confusing proactive with retroactive interference.
• Confusing sensation with perception.
• Attributing top-down processing to Gibson rather than Gregory.
• Confusing the autonomic nervous system’s role with the somatic system’s, or forgetting Broca’s and Wernicke’s areas are for production versus comprehension respectively.
• Confusing the independent and dependent variables.
• Describing a study when the question says evaluate.

Self-test

1. Give the capacity and duration of short-term memory.
2. What is retrieval failure, and what does it explain that decay cannot?
3. What did Bartlett’s study demonstrate?
4. Which theory explains illusions well, and what is its weakness?
5. Distinguish the independent from the dependent variable.

Answers: 1. Five to nine items, held for roughly 18 to 30 seconds. 2. Forgetting caused by the absence of the cue needed to access a stored memory; it explains why a memory can be recovered later with the right prompt, which decay cannot. 3. That memory is reconstructive — recall is shaped by cultural schemas, so details are omitted, shortened or altered to fit expectations. 4. Gregory’s constructivist theory; its weakness is that it struggles to explain how perception is normally so fast and accurate. 5. The independent variable is what the researcher changes; the dependent variable is what is measured.