Topic B: Cognitive psychology AS

Atkinson and Shiffrin's multi-store model treats memory as information moving through three stores. Attention moves selected sensory input into short-term memory (STM); maintenance rehearsal keeps it active and can transfer it to long-term memory (LTM); retrieval returns stored information to STM for conscious use.

Serial-position findings support separate short- and long-term contributions, and preventing rehearsal rapidly reduces STM recall. HM's intact immediate memory but severe difficulty forming new declarative long-term memories also supports separable stores.

Baddeley and Hitch's working-memory model explains short-term memory as an active, limited-capacity system whose components can process different kinds of information at the same time.

Dual-task performance, the word-length effect and cases such as KF support partly separate components. The model also explains why listening to speech while writing verbal notes can overload the phonological system.

Bartlett's reconstructive account proposes that recall combines incomplete memory traces with schemas - organised knowledge built from prior experience and cultural expectations. The result is a plausible reconstruction, not a literal recording.

When details are missing or ambiguous, a schema guides selection and interpretation. Information may be omitted, rationalised, transformed into a more familiar form or added through confabulation. Assimilation changes new information so that it fits an existing schema, although schemas can also be updated by experience.

Two witnesses can encode the same event yet later describe it differently because their expectations about people, places or likely actions fill different gaps. Bartlett's War of the Ghosts and office-schema research found familiar substitutions and recall of schema-consistent items that were not present.

An experiment manipulates an independent variable (IV), measures a dependent variable (DV) and controls alternatives so that a causal explanation can be tested. The laboratory-field distinction concerns the setting and degree of control, not whether an IV exists.

Design from the hypothesis: operationalise IV and DV, choose a design and sample, standardise instructions and timing, control plausible confounds, pilot the task, obtain consent and manage risk, then record data consistently. A control condition provides a baseline when one is needed.

The independent variable is the condition the researcher changes or compares; the dependent variable is the measured outcome expected to respond. Both must be operationalised so another researcher could reproduce exactly what was varied and recorded.

A variable name such as 'noise', 'memory' or 'aggression' is not enough. State the conditions, dose or category for the IV and the observable score, unit, timing and scoring rule for the DV.

An experimental hypothesis predicts that an operationalised IV will affect an operationalised DV. A null hypothesis predicts no difference or relationship in the population and states that any sample pattern is due to chance.

Both hypotheses must identify the population where relevant, the exact conditions and the measured outcome. The experimental hypothesis can be directional or non-directional; the null remains a no-effect statement.

A directional hypothesis predicts which condition will score higher or whether a relationship will be positive or negative. A non-directional hypothesis predicts a difference or relationship without choosing its direction.

Choose the tail before seeing the results. A well-supported theory or consistent previous evidence can justify one-tailed testing; uncertainty or credible effects in either direction calls for two-tailed testing.

Experimental design determines which participants provide data in each condition. The best choice controls the most serious alternative explanation without creating a larger one.

Operationalisation turns an abstract construct into a replicable manipulation or measure. Control then protects the comparison from variables other than the IV.

Before data collection, list plausible situational, participant and material variables. Hold them constant, randomise them, match them or measure them, and standardise instructions and scoring. A pilot can reveal unclear items or ceiling and floor effects.

Controls create a fair comparison by holding an influence constant, distributing it unpredictably or providing a baseline against which the experimental condition can be interpreted.

Practice can improve later performance; fatigue or boredom can reduce it; carry-over means one condition changes response to the next. Counterbalancing estimates and distributes order effects, while independent groups avoids repeated exposure.

Situational variables arise from the environment or procedure; participant variables are stable or pre-existing differences between the people studied. Either can obscure an IV's effect on the DV.

If one memory group has previously played the computer task, prior practice can raise its scores. If one condition is tested in a noisy room, setting can lower its scores. Both become confounds when aligned systematically with the IV.

Research quality has distinct dimensions. Objectivity concerns freedom from researcher judgement; reliability concerns consistency; validity concerns whether the evidence supports the intended interpretation.

Experimenter effects occur when a researcher's expectations or behaviour alter procedures, scoring or participant responses. Demand characteristics occur when participants infer the aim and change their behaviour.

List A analysis matches the summary to the data rather than reporting every available statistic. Quantitative data show amounts; qualitative data show meanings and are analysed through systematic coding and themes.

Inferential statistics ask whether an observed pattern is unlikely under the null hypothesis. Choose a test from the research question, design and lowest level of measurement: nominal categories, ordinal ranks, or interval/ratio equal units.

For Wilcoxon, calculate paired differences, remove zero differences, rank absolute differences with tied ranks averaged, restore signs, total positive and negative ranks, and use the smaller total as $T$. Select the critical value using $N$, the chosen $p$ level and one- or two-tailed prediction.

At $p\le .05$, a result this extreme would occur by chance no more than 5% of the time if the null were true. A stricter $p$ reduces Type I risk - rejecting a true null - but increases Type II risk - failing to reject a false null. Sense-check impossible values, coding errors, outliers, sample size and whether the direction matches the hypothesis before concluding.

A case study investigates one unusual person or a small group in depth, often combining interviews, observations, memory tasks, records and brain imaging over time. Naturally occurring brain damage provides evidence that could not ethically be created experimentally.

After surgery involving the medial temporal region to treat epilepsy, Henry Molaison (HM) retained immediate memory and older memories but could not form normal new declarative long-term memories. Yet his mirror-drawing skill improved without conscious recollection, separating STM from LTM and procedural from declarative memory.

Memory impairment can limit continuing informed consent, and recognisable cases challenge anonymity. Researchers need capacity-sensitive consent, assent and proxy procedures where justified, privacy, minimal burden, withdrawal safeguards and sensitive handling of distressing information.

Bartlett tested how cultural schemas shape recall of an unfamiliar Native American story. Cambridge participants read War of the Ghosts and reproduced it after delays, either repeatedly themselves or through a chain of different people.

Across reproductions, accounts became shorter, more coherent and more conventional to the participants. Unfamiliar details were omitted or transformed: for example, canoes became boats and supernatural material faded. The pattern supports reconstructive memory because recall moved systematically toward familiar schemas.

Using the same unusual story helped reveal schema-driven changes, and the findings apply to eyewitness accounts and transmission of stories. However, the small culturally narrow sample, inconsistent recall intervals and limited procedural detail reduce generalisability and replicability; an unfamiliar story is also unlike many everyday memories.

Schmolck et al. examined whether the extent of temporal-lobe damage predicted loss of semantic knowledge. Six memory-impaired patients - including HM and people with damage extending into lateral temporal cortex - were compared with eight controls.

Participants completed nine tests using common objects and drawings, including naming, pointing, category judgements and verbal definitions. Responses were scored quantitatively; fourteen raters checked definition quality in one task, reducing subjective coding.

Patients whose damage was limited mainly to the hippocampal formation performed normally on semantic tests, while extensive lateral temporal damage was associated with severe, consistent semantic deficits. HM's modest language weakness was judged more consistent with interrupted education than the lesion pattern.

Multiple converging tasks and inter-rater checks strengthen reliability and the link between lesion extent and semantic performance. Yet six unique patients cannot represent all brain damage; lesion groups differed in more than one respect, and picture categorisation is an artificial sample of everyday semantic use.

Darling, Della Sala and Logie tested whether visual appearance and spatial location rely on separable parts of visuo-spatial working memory. Seventy-two adults from a volunteer panel were randomly allocated across combinations of memory and interference tasks.

Participants remembered either the visual appearance of a target on a black-and-white display or its spatial location. During retention they completed selective secondary tasks intended to interfere with appearance or location processing; response latency and accuracy indexed memory performance.

Interference showed an experimental double dissociation: appearance interference selectively disrupted appearance memory, while spatial interference selectively disrupted location memory. This supports separate visual and spatial subsystems rather than one undifferentiated sketchpad.

Random allocation, standardised displays and selective dual-task interference support internal validity and replication. However, a volunteer sample and simplified screen task limit population and ecological validity, and slower responses may reflect task coordination as well as memory storage.

Sacchi, Agnoli and Loftus tested whether altered photographs change memory for public events. Italian participants saw original or digitally doctored photographs of the 1989 Tiananmen Square protest and a 2003 anti-war protest in Rome, then answered questions about the events.

The Beijing image was altered to show a larger crowd; the peaceful Rome scene was altered to show confrontation. Photograph combinations were randomised and counterbalanced before participants completed event-memory and attitude questions.

The enlarged Beijing image led to estimates of more participants. The altered Rome image produced memories of greater violence, confrontation, damage and injuries, more negative ratings, and less willingness to join a future protest. Both younger and older adults were affected.

Real public events and media-like images give the misinformation effect practical relevance, while controlled versions support causal comparison. However, the student-heavy, female-skewed sample limits population validity; questionnaires invite social desirability, and some responses may reflect changed beliefs or source judgements rather than a detailed episodic false memory.

The practical is an ethical repeated-measures laboratory experiment that collects quantitative cognitive data and tests a difference with Wilcoxon signed ranks. Every decision must connect the hypothesis, manipulation, measurement and conclusion.

Suitable designs include a dual-task test of phonological or visuospatial working memory, or recall of acoustically similar versus dissimilar words. Use equivalent word lists and a counterbalanced order so practice, fatigue and material difficulty do not become confounds.