Unit 2: Biological psychology AS, learning theories and development

The central nervous system (CNS) consists of the brain and spinal cord. It receives information from sensory systems, integrates it and sends signals that coordinate responses. Neurons carry information within this system; neurotransmitters carry a chemical signal across the tiny gap between neurons.

When an impulse reaches a terminal, vesicles release neurotransmitter into the synaptic cleft. Molecules diffuse across, bind to matching receptors and can excite or inhibit the postsynaptic neuron. The transmitter is then removed, for example by reuptake or enzymatic breakdown, so the signal is controlled rather than remaining permanently active.

Aggression is linked to coordinated brain systems for threat, emotion and control. The prefrontal cortex helps evaluate consequences and inhibit impulsive responses; limbic structures help detect emotionally significant events and organise defensive responses.

Brain scans and lesion cases can show that activity or damage is associated with aggression. Raine et al. found group differences across several regions in murderers who pleaded not guilty by reason of insanity, including reduced prefrontal activity. The pattern supports a network account rather than a single 'aggression centre'.

Hormones and genes can influence systems involved in arousal, threat and impulse control, but they do not make aggression inevitable. Their effects vary with development, situation and learning.

A useful model is gene-environment interaction: a biological variant may change sensitivity to provocation, while the environment supplies the trigger and the learned response options. McDermott et al. found the clearest MAOA group difference under high monetary provocation, illustrating this conditional effect.

The sleep-wake cycle is circadian: it repeats roughly every 24 hours. An internal pacemaker produces the rhythm, while external zeitgebers provide time cues that synchronise it to the environmental day.

After night work or rapid travel, the internal clock can remain aligned with the previous light schedule. Morning light may suppress melatonin and raise alertness just when a night worker is trying to sleep. Timed light and regular routines can gradually shift the rhythm.

An infradian rhythm has a period longer than 24 hours. The menstrual cycle and the seasonal pattern of seasonal affective disorder (SAD) are examples, but each involves different biological processes.

Bright-light therapy aims to replace a missing seasonal light cue. A person typically uses a suitable light box in the morning on a regular schedule; light shifts circadian timing and can reduce excessive daytime melatonin-related sleepiness. Treatment strength, timing, eye or medication risks and professional advice matter.

Research on bodily rhythms must separate an internally generated cycle from the environmental cues that reset it. Different methods provide complementary evidence, but each leaves a different alternative explanation.

Judge a claim by design: an experiment can strengthen causal inference through manipulation and control; a case study provides depth; a correlation or longitudinal study shows association and change over time. Replication across methods is stronger than one dramatic finding.

A correlation measures whether two co-variables vary together. Neither co-variable is manipulated, so the method describes a relationship rather than an experimental effect.

Correlations are useful when variables occur naturally or cannot ethically be manipulated, such as age, hormone level or sleep habits. Operational definitions, a suitable sample and a consistent procedure make the measurements replicable. A scatter diagram and correlation coefficient then show direction and strength.

A scatter diagram plots one paired score as one point. The overall pattern shows the direction and approximate strength of a relationship; the axes do not decide which variable causes the other.

Give the graph an informative title, label both axes with the operationalised co-variable and unit, choose a scale that uses the plotting area, and plot every paired score accurately. Inspect possible outliers because one unusual case can change the apparent pattern and the coefficient.

A correlation cannot establish cause and effect because its design does not manipulate one variable while controlling alternatives. Two main uncertainties remain even when the coefficient is strong.

Strengthen interpretation by measuring plausible third variables, using validated or objective measures, sampling a wider relevant population and following participants over time. A controlled experiment can test a causal hypothesis when manipulation is ethical, but it answers a narrower question than the original natural correlation.

Spearman's rank correlation coefficient, $r_s$, tests the strength and direction of a monotonic relationship between paired scores measured at least at the ordinal level. It is appropriate when the research question is correlational and the scores can be ranked.

$d$ is the difference between a case's two ranks and $n$ is the number of paired cases. Rank both co-variables in the same direction, give tied scores their mean rank, calculate each $d$ and $d^2$, sum $d^2$, then substitute and sense-check that $-1\le r_s\le1$. The sign gives direction; closeness to $1$ or $-1$ gives strength.

Brain-scanning techniques differ in what they measure. CAT is mainly structural; PET and fMRI can index function. The technique must match the research question, safety constraints and required detail.

To study aggression, researchers can compare activity in specified regions during a standard task or compare groups with carefully matched controls. Operationalising the task, pre-registering regions and using blind, consistent analysis reduces selective interpretation.

Twin studies compare similarity in monozygotic (MZ) twins, who share virtually all their segregating genes, with dizygotic (DZ) twins, who share on average about half. If MZ aggression is more concordant than DZ aggression, genetic influence is plausible.

A higher MZ similarity supports heritability within the studied population and environment. Shared environmental influence makes twins alike; non-shared experiences and measurement error make them differ. Brendgen et al. used peer and teacher ratings to compare physical and social aggression in six-year-old twins.

List A provides the descriptive tools used across psychology. Choose a summary from the data type and distribution rather than calculating every statistic available.

Label tables and axes, retain units, check totals and denominators, and inspect unusual scores before choosing the mean or standard deviation. Descriptive statistics summarise the sample; they do not show whether a relationship or difference is statistically significant.

Raine et al. tested whether people charged with murder or manslaughter who pleaded not guilty by reason of insanity (NGRI) showed different brain functioning from matched controls.

The study compared 41 NGRI participants (39 men and 2 women) with 41 controls matched on sex and similar characteristics. Participants completed a 32-minute continuous performance task after receiving a glucose tracer, then underwent PET scanning. Regional glucose metabolism was compared with cortical-peel and region-of-interest methods.

PET provided objective physiological data and matching reduced several participant differences. However, the selected NGRI sample is not representative of all murderers, the CPT was not an aggressive task, medication history and diagnosis complicate interpretation, and the design cannot show that brain differences caused the offences.

Brendgen et al. asked whether genetic, shared-environment and non-shared-environment influences differ for physical aggression and social aggression in six-year-old twins.

The longitudinal Montreal sample included 234 twin pairs. Same-sex twins were classified for zygosity mainly from physical resemblance at 18 months, with a proportion checked using DNA. At age six, peers selected photographs matching behavioural descriptions, while teachers completed established social and physical aggression scales. Parents provided written consent.

Agreement across peer and teacher methods strengthens reliability, and the large twin sample permits genetic modelling. Yet appearance-based zygosity can be wrong, peers may nominate after recent conflict, ratings do not directly observe every act, and six-year-old mostly European-descent Montreal twins limit age and cultural generalisation.

McDermott et al. tested whether MAOA activity predicts costly aggressive punishment and whether its effect changes with environmental provocation.

Genetic samples from 78 male participants classified them as high-activity (MAOA-H) or low-activity (MAOA-L). In four rounds of a power-to-take game, a fictional opponent removed either 20% or 80% of money earned on a vocabulary task. Participants could pay to give that opponent unwanted hot sauce; whether and how much they allocated operationalised aggression.

High provocation increased aggression overall, and the low-activity group responded most strongly when 80% was taken. This supports a gene-environment interaction: genotype altered sensitivity to provocation rather than producing the same behaviour in every situation.

Hoefelmann et al. compared cross-sectional and prospective links between lifestyle behaviours and self-reported sleep quality and duration in Brazilian high-school students.

The secondary analysis used data from students aged 14-24 in 20 public schools. Of 2,000 initially selected, 989 completed baseline and nine-month assessments; 949 supplied longitudinal sleep-quality data and 950 sleep-duration data. Closed questionnaire items measured activity, screen use, food, soft drinks, alcohol, perceived sleep quality and daily sleep duration.

Poor perceived sleep and insufficient duration were common and stable, but an association measured at one time did not become a prospective prediction. This contrast demonstrates why cross-sectional correlation is weak evidence of causal direction.

A biological-psychology practical must test a relationship between two operationalised co-variables, gather paired quantitative data ethically and report association without claiming causation.

Suitable questions include the relationship between daily social-media time and average nightly sleep, or height in centimetres and a score from an established self-rated aggression scale. A diary or device can improve sleep-time validity; anonymous responses can reduce social-desirability pressure for aggression.

Classical conditioning explains learning of reflexive, involuntary responses. A stimulus that naturally produces a response is paired with a previously neutral stimulus until that neutral stimulus can produce a learned response on its own.

Food naturally produces salivation, so food is the unconditioned stimulus (UCS) and salivation the unconditioned response (UCR). If a buzzer is repeatedly paired with food, the buzzer becomes the conditioned stimulus (CS) and salivation to it is the conditioned response (CR). Watson and Rayner applied the same logic to fear learning.

Operant conditioning explains how consequences alter the future frequency of voluntary behaviour. Reinforcement increases behaviour; punishment decreases it. Positive means something is added and negative means something is removed—it does not mean good or bad.

Primary reinforcers meet biological needs; secondary reinforcers acquire value through association. Continuous reinforcement can establish a response quickly, while intermittent schedules often make it more resistant to extinction. Shaping reinforces successive approximations until the target behaviour is reached.

Social learning theory proposes that people can learn by observing models and the consequences those models receive. Learning can occur without immediate performance, so observation is not the same as automatic imitation.

A model is more influential when the learner identifies with them—for example through perceived similarity, status or attractiveness. Direct reinforcement affects the learner’s own behaviour; vicarious reinforcement occurs when observing another person rewarded and makes imitation more likely. Observed punishment can inhibit performance.

Freud proposed that behaviour is influenced by unconscious conflict. The id seeks immediate gratification, the ego negotiates with reality, and the superego represents internalised moral standards. Anxiety arises when these demands conflict, and defence mechanisms protect the ego by distorting or redirecting experience.

In the phallic stage Freud described the Oedipus conflict and identification with the same-sex parent as routes to superego development. These are historical theoretical claims, not established facts about every child. Object-relations approaches instead emphasise how early caregiver relationships become internal templates for later relationships.

Systematic desensitisation is a behavioural treatment for phobias. It uses counterconditioning: relaxation is paired with gradually stronger versions of the feared stimulus so that a calm response competes with anxiety. This is often described as reciprocal inhibition.

Exposure may be imagined or in vivo. Small achievable steps and client control can make treatment acceptable, while repeated practice weakens avoidance and provides new evidence that the situation is manageable. Capafóns et al. applied a standardised hierarchy-based programme to fear of flying.

Psychoanalysis aims to make unconscious conflicts and relationship patterns conscious so that they can be understood rather than repeatedly acted out. The therapist listens for recurring meanings rather than treating one statement as a direct measurement of the unconscious.

Interpretations should be tentative and developed through the therapeutic relationship. Insight may help a client notice a repeated defence or relationship pattern and try a different response.

Observation records behaviour as it occurs. A useful design turns an aim into mutually clear behavioural categories, a sampling rule and a recording system, so another observer could apply the same decisions.

Natural settings can improve ecological validity; structured settings provide more control. Observers need the same viewpoint and rules. Where practical, video allows checking, but recording requires specific consent and secure handling.

Observation designs are classified along independent dimensions. A study may be participant and naturalistic, or non-participant and structured; overt/covert describes awareness rather than setting.

Choose the combination from the research question. If the aim is to count helping under identical conditions, a structured non-participant observation may improve comparability. To understand naturally occurring group behaviour, a participant naturalistic design may supply richer context.

Content analysis is a systematic method for examining communication such as articles, posts, interviews or videos. It can produce quantitative counts, qualitative interpretations, or both, but its sampling and coding rules must be explicit.

A coding manual should include definitions and borderline examples. Quantitative counts improve transparency; qualitative notes can preserve context. Anonymise personal material and respect copyright, privacy and the expectations of the source community.

Freud developed psychodynamic ideas through intensive case studies of individual clients. Case material could include interviews, free association, dreams, slips and remembered childhood events, producing an idiographic account of one person over time.

A strong case report separates what the client said or did from the analyst’s interpretation, preserves confidentiality, considers alternative explanations and avoids claiming that improvement proves the theory.

List A supplies descriptive tools used throughout psychology. The choice depends on measurement level, distribution and the question; computing every statistic does not improve an analysis.

Inspect unusual scores, verify totals and use consistent units. A labelled graph communicates the operationalised variable, while a table should allow the reader to reconstruct how the summary was obtained.

Thematic analysis identifies patterned meaning in qualitative data. It can be inductive, allowing codes to arise from the material, or deductive, applying concepts chosen in advance. Either way, the researcher must show how interpretation was produced.

A reflexive log records how assumptions and decisions affected the analysis. A second coder can test whether a structured codebook is applied consistently, while discussion of disagreements can reveal ambiguous definitions. Frequencies may supplement a theme but do not create it.

The chi-square test of independence compares observed frequencies in a contingency table with frequencies expected if two categorical variables were unrelated. Data must be counts in mutually exclusive categories, with each case contributing to one cell.

For each cell, calculate $E=( ext{row total} imes ext{column total})/ ext{grand total}$. Then calculate each contribution $(O-E)^2/E$ and add them. Degrees of freedom are $(r-1)(c-1)$. Check expected frequencies and the table required by Pearson before interpreting the statistic.

UK animal research is governed by the Animals (Scientific Procedures) Act 1986 and Home Office licensing. Legal permission does not end ethical evaluation: the likely scientific or social benefit must justify the harms and no suitable less harmful method should answer the question.

Animals allow controlled, invasive or developmental research that could not ethically be conducted on humans. Standardisation may strengthen causal inference, but stress, artificial housing and species differences can change behaviour and restrict generalisation.

Watson and Rayner investigated whether an emotional response could be classically conditioned, generalise to similar objects and persist over time in a young child known as Albert.

At about nine months Albert showed no fear of a white rat, rabbit, dog, monkey, masks, fur or burning newspaper, but a hammer striking a steel bar startled him. At 11 months the rat was paired with the loud noise. Later tests presented the rat alone, similar furry objects and a different room; blocks were used between trials to calm him.

Capafóns et al. tested whether systematic desensitisation reduced fear of flying. Forty-one media-recruited volunteers were randomly allocated to treatment ($n=20$) or no-treatment control ($n=21$); groups did not differ on pre-treatment measures.

Interviews and established scales measured flight fear, catastrophic thoughts and physiological symptoms. Heart rate, muscle tension and skin temperature were recorded while participants watched a video covering a journey from packing to landing. Treatment involved two one-hour sessions per week, at least 12 and at most 15, using a hierarchy, brief relaxation, thought stopping, imagery and in-vivo techniques.

Prot et al. examined links among prosocial-media use, empathy and prosocial behaviour, including whether age, gender and culture moderated them. The researchers used complementary cross-sectional and longitudinal studies.

Across cultural groups, greater prosocial-media use was associated with greater empathy and prosocial behaviour. At each longitudinal wave the same positive relationships appeared; Time 1 prosocial-game use predicted greater Time 3 prosocial behaviour, while violent-game use predicted less. Changes in empathy helped explain these links.

Bastian et al. tested whether violent game play changes how human participants perceive themselves and other players. Random allocation compared violent and non-violent games, allowing a stronger causal inference for the immediate laboratory effect.

Participants rated human-nature qualities after play. Study 2 also measured mood with PANAS and state self-esteem to test whether a general negative feeling explained the result. The reported self-humanity difference remained the central finding.

The Topic D practical uses observation to investigate learned behaviour. It must include two observations, or one observation producing both qualitative and quantitative data, and report what was recorded rather than inferring motives.

A structured observation might compare frequencies of clearly defined helpful acts across two contexts. If categories include perceived gender or age, state how observers coded it, recognise uncertainty and avoid treating group differences as innate or binary. Driving speed or politeness can be recorded only with safe, lawful procedures.