AQA A-Level Psychology: Paper 2 - Psychology in Context

Types of neuron:

Neuron structure:

• Dendrites: receive impulses from neighbouring neurons.
• Cell body (soma): contains the nucleus.
• Axon: carries the electrical impulse (action potential) away from the cell body.
• Myelin sheath: fatty layer insulating the axon to speed up impulse transmission.
• Nodes of Ranvier: gaps in the myelin sheath that allow the impulse to "jump" - speeding transmission.
• Axon terminals: ends of the axon containing synaptic vesicles with neurotransmitters.

Electrical transmission: when a neuron is in a resting state, the inside of the cell is negatively charged relative to the outside. When activated by a stimulus, it becomes positively charged for a split second - causing an action potential to travel down the axon.

Synaptic transmission: when an action potential reaches the axon terminal:

1. Synaptic vesicles release neurotransmitters into the synaptic cleft (gap between neurons).
2. Neurotransmitters diffuse across and bind to receptor sites on the postsynaptic neuron.
3. This triggers either an excitatory postsynaptic potential (e.g. noradrenaline - makes the postsynaptic neuron more likely to fire) or an inhibitory postsynaptic potential (e.g. GABA - makes it less likely to fire).
4. The postsynaptic neuron sums all excitatory and inhibitory inputs (summation). If the net result is sufficiently positive (above threshold), the neuron fires its own action potential.
5. Neurotransmitters are then either broken down by enzymes or reuptaken back into the presynaptic neuron.

Endocrine system: a network of glands throughout the body that release hormones into the bloodstream to regulate organ function. Works alongside the nervous system but slower and longer-lasting.

Fight-or-flight response (Cannon, 1932):

1. The amygdala in the brain detects a threat.
2. It signals the hypothalamus, which activates the sympathetic nervous system (SNS).
3. The SNS stimulates the adrenal medulla to release adrenaline and noradrenaline into the bloodstream.
4. Physiological responses: heart rate ↑, blood pressure ↑, pupils dilate, breathing rate ↑, digestion inhibited, glucose released from liver, blood diverted to muscles - prepares body to fight or flee.
5. Once the threat passes, the parasympathetic nervous system takes over - "rest and digest" - returning the body to baseline.

HPA axis (slower, longer-term stress response): hypothalamus → releases CRH → pituitary releases ACTH → adrenal cortex releases cortisol. Sustained high cortisol can damage immune function and memory.

Evaluation:

• Real-world application: understanding fight-or-flight helps explain anxiety disorders and informs stress management interventions.
• "Tend and befriend" (Taylor et al., 2000): argued the fight-or-flight response is androcentric - females may respond to stress by tending to offspring and seeking social support, due to evolutionary differences and the hormone oxytocin.
• Negative consequences of chronic activation: repeated activation increases cardiovascular risk, immune suppression (Tomova et al., 2014).
• Freeze response: Gray (1988) - the first response to threat is often to "freeze" (stop, assess), not fight or flee.

Localisation of function: the theory that specific areas of the brain are responsible for specific physical and psychological functions. Contrast: holistic theory (all parts of the brain involved in all functions; Lashley, 1950).

The cerebrum is divided into two hemispheres (left/right) each further divided into four lobes:

Language centres (left hemisphere - lateralised in most people):

Evaluation:

• Brain scan evidence: Petersen et al. (1988) used PET scans showing Broca's area active during a reading task, Wernicke's active during a listening task - supports localisation.
• Neurosurgical evidence: Dougherty et al. (2002) - 32 OCD patients underwent cingulotomy (lesioning specific brain area); 30% achieved successful response, 14% partial - supports localisation of OCD-related circuits.
• Case study evidence: Phineas Gage (1848) - iron rod through left frontal lobe; survived but his personality changed (irritable, impulsive). Suggests the frontal lobe has a role in personality/regulation.
• Plasticity challenges strict localisation: Lashley (1950) - rats with cortex damage could still learn mazes; suggests learning is distributed (equipotentiality). Modern view: localisation + distribution.
• Communication is important: language likely involves a network of areas (Broca, Wernicke, arcuate fasciculus) - oversimplifying to one area is misleading.

Hemispheric lateralisation: the two cerebral hemispheres are functionally different. Left hemisphere dominant for language and analytical processing; right hemisphere dominant for spatial, holistic, and emotional processing. The two hemispheres communicate via the corpus callosum.

Sperry (1968) - split-brain research: studied 11 patients who had undergone commissurotomy - surgical cutting of the corpus callosum to treat severe epilepsy. After surgery, the hemispheres could no longer communicate, allowing each to be tested in isolation.

Procedure: participants fixated on a central point; words or images were projected to either the right visual field (RVF → left hemisphere) or the left visual field (LVF → right hemisphere) for ~1/10 of a second (too quick for eye movement).

Key findings:

• Object presented to RVF (left hemisphere): participants could verbally describe it (left hemisphere has language).
• Object presented to LVF (right hemisphere): participants could NOT verbally describe it, but could draw it with their left hand or pick out the matching object by touch with their left hand. (Right hemisphere recognises but cannot speak.)
• Synthesis impossible across hemispheres: if one image shown to each hemisphere, participants treated them separately without integrating.

Conclusion: language is lateralised to the left hemisphere; the right hemisphere has limited language ability but can recognise objects and produce drawings. Strong evidence for lateralisation.

Evaluation:

• Standardised procedure: Sperry used a carefully designed setup that has been replicated and supports the conclusions.
• Some lateralisation evident in everyday tasks: Fink et al. (1996) used PET scans on neurotypical participants - found left hemisphere active during detailed analysis (e.g. focusing on a tree); right hemisphere for overall ("forest").
• Generalisation issues: the patients had epilepsy and surgery, which may have caused atypical brain organisation; small sample (n = 11).
• Differences in lateralisation may be exaggerated: in everyday life the hemispheres work together via the corpus callosum; popular "left-brained vs right-brained" personality claims are not supported.
• Ethical issues: some argue the patients were too easily exploited as research participants; however, valuable scientific knowledge resulted.

Brain plasticity (neuroplasticity): the brain's ability to change and adapt as a result of experience and new learning. The brain forms new synaptic connections and prunes unused ones. Most plasticity occurs in childhood but continues throughout life.

Maguire et al. (2000) - London taxi drivers: using MRI, found taxi drivers had a significantly larger posterior hippocampus (used for spatial memory) than a control group. The longer they had been driving, the more pronounced the difference. Demonstrates structural plasticity.

Draganski et al. (2006): imaged medical students' brains before and after their exams - found learning-induced changes in the posterior hippocampus and parietal cortex. Shows plasticity in adults from short-term learning.

Functional recovery (a form of plasticity): after brain damage (e.g. stroke, trauma), unaffected areas of the brain can adapt and compensate for damaged ones. The brain rewires by:

• Axonal sprouting: growth of new nerve endings that connect with other undamaged neurons.
• Reformation of blood vessels in damaged areas.
• Recruitment of homologous areas on the opposite hemisphere (e.g. if Broca's area damaged, the right-hemisphere equivalent may take over).
• Denervation supersensitivity: axons becoming aroused by similar electrical impulses to compensate for damaged ones.

Evaluation:

• Real-world application: understanding has led to neurorehabilitation programmes following stroke or trauma (e.g. constraint-induced movement therapy).
• Negative plasticity: Medina et al. (2007) - prolonged drug use can produce poorer cognitive functioning and dementia; phantom limb pain - reorganisation of somatosensory cortex causes pain perception in a missing limb (Ramachandran & Hirstein, 1998).
• Age and recovery: Bezzola et al. (2012) - 40 hours of golf training in 40-60-year-olds led to changes in motor cortex - functional recovery is not limited to young people.
• Cognitive reserve: Schneider et al. (2014) - more education (cognitive reserve) was associated with better recovery from brain injury - suggests pre-existing brain organisation affects recovery.
• Recovery is not always complete: severe damage may produce only partial recovery; not all neurons regenerate.

Spatial vs temporal resolution:

Types of variable:

• Independent variable (IV): what the experimenter manipulates.
• Dependent variable (DV): what is measured.
• Extraneous variables (EVs): any variables, other than the IV, that may affect the DV. Must be controlled.
• Confounding variables: EVs that have systematically varied with the IV, making it impossible to determine which is responsible for the change in DV.

Randomisation vs random allocation: these are different control methods. Random allocation assigns participants to conditions by chance (removes individual difference confounds in independent groups design). Randomisation refers to randomising the order of trials or stimuli within a study (for example, presenting words in a different random order for each participant) so that order bias does not affect results.

Target population: the group from which the sample is drawn. Sample: the participants actually taking part. A representative sample reflects the population characteristics.

BPS Code of Ethics (2018) sets four principles: respect, competence, responsibility, integrity. Key ethical issues:

Cost-benefit analysis: ethical committees weigh the scientific value of a study against the potential harm to participants before approving it.

Observational techniques:

Sampling in observations: event sampling (count every occurrence of an event); time sampling (record what's happening at set intervals, e.g. every 30 s).

Self-report techniques:

Correlations: investigate the relationship between two co-variables (no IV is manipulated).

• Positive correlation: as one variable increases, so does the other (e.g. study hours and exam grade).
• Negative correlation: as one variable increases, the other decreases (e.g. screen time and sleep duration).
• Zero correlation: no relationship.
• Correlation coefficient (r): ranges from -1 (perfect negative) through 0 (none) to +1 (perfect positive).
• Strengths: can study variables that cannot be ethically manipulated; can suggest hypotheses. Limitations: correlation ≠ causation; third (intervening) variables; non-linear relationships missed.

Strengths: useful where direct experiment is impossible; high ecological validity (real-world data). Limitations: researcher bias in coding; lacks control of context; can become reductive if reducing qualitative themes to numerical counts.

Primary vs secondary data and meta-analysis:

Validity: the extent to which results measure what they claim to measure / generalise.

Improving validity: use control groups; standardised procedures; reduce demand characteristics (e.g. single-blind, double-blind designs); use anonymous self-reports to reduce social desirability bias.

Reliability: the consistency of findings.

Improving reliability: standardised procedures; clear, operationalised behavioural categories; training of observers; pilot studies to refine tests.

Peer review: the assessment of scientific work by other experts in the same field before publication. Purposes: (1) allocation of funding; (2) publication of research in journals; (3) assessing the quality and accuracy of work.

Strengths: maintains research quality; spots errors and bias. Limitations: reviewers may have biases (anonymity is supposed to protect against this but doesn't always); publication bias toward positive/novel findings; slow process; can discourage controversial or paradigm-challenging work.

Features of science (key features for AQA):

• Objectivity: minimising researcher bias - all observations are made impartially, separate from the researcher's personal views.
• The empirical method: knowledge built through direct, systematic observation and measurement, not opinion.
• Replicability: studies must be repeatable to verify findings; ensures generalisability and reliability.
• Falsifiability (Popper, 1934): a scientific theory must be capable of being shown wrong (testable predictions). Theories that are unfalsifiable (e.g. some psychodynamic concepts) are pseudo-scientific.
• Theory construction and hypothesis testing: theories generate falsifiable hypotheses tested through research; results refine the theory.
• Paradigms and paradigm shifts (Kuhn, 1962): a paradigm is a shared set of assumptions about the field. A paradigm shift occurs when accumulated evidence overturns the existing paradigm (e.g. behaviourism → cognitive revolution). Kuhn argued psychology lacks a single paradigm so is a "pre-science"; others disagree.

Implications of psychological research for the economy: psychological research influences economic productivity, well-being, and policy:

• Treatments for mental illness: CBT and drug therapies reduce time off work due to depression/anxiety (estimated cost: £100+ billion/year to UK economy).
• Workplace psychology: motivation theories (Maslow, Herzberg) inform management practice and increase productivity.
• Eyewitness testimony research: changes how police interview, reducing wrongful convictions and miscarriages of justice (which are costly).
• Attachment research: informs childcare policies, parental leave, and adoption practice.
• Cognitive research: education and learning techniques.

Psychological research reports follow a standardised structure (APA style):

Levels of measurement (NOIR):

Measures of central tendency:

Measures of dispersion (spread):

Distributions:

• Normal distribution: bell-shaped, symmetrical. Mean = median = mode at the peak. ~68% of scores within ±1 SD; ~95% within ±2 SD; ~99.7% within ±3 SD.
• Skewed distributions: not symmetrical. Positive skew: long tail to the right; most scores clustered at low values; mean > median > mode (e.g. a very hard test). Negative skew: long tail to the left; most scores clustered at high values; mode > median > mean (e.g. a very easy test).

Visual displays: bar charts (nominal/categorical data); histograms (continuous data); scattergrams (correlations); line graphs (changes over time).

The sign test is a simple non-parametric test for the AS-level. It is used when:

• Looking for a difference (not a relationship).
• Using related (paired) data - repeated measures or matched pairs.
• Data is nominal (categorical) - or can be converted to nominal (e.g. "got better" / "got worse" / "no change").

Procedure:

1. For each pair of scores, calculate the direction of change (+, -, or 0).
2. Discard zero scores (no change).
3. Let N = the total number of non-zero scores.
4. Let S = the smaller number of either + or - signs (the "less common" sign).
5. Compare S to the critical value from the sign-test table (based on N, significance level (p ≤ 0.05), and tail direction).
6. If S ≤ critical value: reject the null hypothesis (result is significant). If S > critical value: retain the null hypothesis.

Worked example: 10 participants rated mood before and after exercise (1-7 scale). 8 improved (+), 1 worsened (-), 1 no change (0).

Probability and significance:

• p value: the probability that the observed result occurred by chance.
• Conventional significance level: p ≤ 0.05 (5% chance the result is due to chance). Sometimes stricter levels are used (e.g. p ≤ 0.01) for more critical research.
• Type I error (false positive): rejecting the null hypothesis when it is true; more likely with lenient p values.
• Type II error (false negative): retaining the null when it is false; more likely with strict p values or small samples.

To choose the correct inferential test, ask three questions:

1. Difference or correlation?
2. Related or unrelated data? (related = repeated measures/matched pairs; unrelated = independent groups)
3. What level of measurement? (nominal / ordinal / interval+ratio)

The 7-test summary table (AQA spec):

Mnemonic: "Carrots Should Come Mashed With Suede Under Roast Potatoes" - Chi-squared, Sign test, Chi-squared, Mann-Whitney U, Wilcoxon, Spearman, Unrelated t, Related t, Pearson.

Parametric vs non-parametric:

Critical values: determined by significance level, N (or df = degrees of freedom), and one-tailed vs two-tailed (directional vs non-directional hypothesis). Each test has a specific critical-value table to compare with the calculated value.

Rules for significance:

• For Mann-Whitney U, Wilcoxon T, Sign test, Spearman's ρ: calculated value must be LESS than or equal to critical value for significance.
• For t-test, Chi-squared, Pearson's r: calculated value must be GREATER than or equal to critical value for significance.

Single-blind: participants don't know which condition they're in. Double-blind: neither participant nor experimenter knows. Used commonly in drug trials and reduces both demand characteristics and investigator effects.