Topic 3: Biological psychology

Overview

Biological Psychology (Topic 3) examines the physical basis of human behaviour. Rather than looking at childhood experiences or cognitive processes, this approach argues that to understand the mind, we must first understand the brain. Examiners expect candidates to confidently discuss the central nervous system, synaptic transmission, and the role of hormones, particularly in relation to aggression.

This topic is historically significant because it shifted psychology towards the natural sciences, utilising objective scanning methods like PET and fMRI. A major focus is comparing biological explanations of aggression with Freud's psychodynamic approach, and understanding the classic Raine et al. (1997) study on murderers' brains.

Key Concepts & Biological Mechanisms

The Neuron and Synaptic Transmission

Structure: Neurons are specialised cells transmitting electrical and chemical signals. Key parts include the cell body, dendrites, axon, and myelin sheath.

Process: Signals travel electrically down the axon but cross the synaptic cleft chemically via neurotransmitters (e.g., serotonin, dopamine). These bind to receptor sites on the postsynaptic neuron.

Exam Relevance: You must be able to describe this process sequentially. Examiners often ask how recreational drugs affect transmission (e.g., blocking reuptake).

Brain Structure and Aggression

The Prefrontal Cortex: Located at the front of the brain, this area regulates emotion and impulse control. Dysfunction here is heavily linked to aggressive behaviour.

Hormones: Testosterone is the primary hormone linked to aggression. Remember that correlation does not equal causation—testosterone levels can rise as a result of aggression, not just cause it.

The Classic Study: Raine et al. (1997)

Aim: To investigate whether murderers who pleaded not guilty by reason of insanity (NGRI) showed brain abnormalities compared to a control group.

Method: A quasi-experiment using PET scanning. 41 murderers (39 men, 2 women) were matched with 41 controls.

Findings: Murderers showed significantly reduced glucose metabolism in the prefrontal cortex compared to controls.

Conclusion: Reduced prefrontal cortex activity may predispose individuals to violence by impairing impulse control.

Explaining Aggression: Biological vs Psychodynamic

Examiners frequently ask for comparisons between these two approaches. The biological approach focuses on measurable physical factors (brain structure, genes). Freud's psychodynamic approach focuses on the unconscious mind, proposing that aggression stems from the 'id' and requires 'catharsis' to be released safely.

Research Methods in Biological Psychology

Brain Scanning Techniques

• CAT Scans: Uses X-rays for 3D structural images. Good for finding tumours, but shows no brain activity.
• PET Scans: Measures glucose metabolism to show brain activity (used by Raine). Involves radioactive tracers.
• fMRI: Measures blood flow in the brain. Excellent spatial resolution and non-invasive.

Correlational Research

Measures the relationship between two co-variables without manipulation. Displayed on scatter diagrams. The inferential test used is Spearman's rho.

Crucial Exam Rule: Correlation does not equal causation.

Podcast Revision

Listen to the revision podcast for a full walkthrough of the topic, exam tips, and a quick-fire recall quiz.