The role of the brain

Psychology is a science: it builds knowledge by asking testable questions, collecting empirical evidence systematically and revising explanations when new evidence appears. Some of its oldest questions, however, began as philosophy. The mind-body problem asks how mental experience (thoughts, feelings, choices) relates to the physical body. A materialist approach claims that the mind is produced by physical matter, especially the brain.

The physician Claudius Galen, working in the Roman Empire in the second century CE, is linked with this view: he served as doctor to gladiators and experimented on animals, and he argued that the brain, rather than the heart, is the source of sensation and voluntary movement and the seat of reason.

A dualist approach, linked with the seventeenth-century French philosopher René Descartes, treats the mind as non-physical and separate from the body, although the two interact; Descartes suggested the pineal gland as their meeting point. The mind-body problem connects with two debates introduced in this unit: free will versus determinism (the view that behaviour is caused by earlier events) and nature versus nurture. These debates continue to shape how evidence is interpreted.

Early investigators tried to locate mental functions in the brain. Franz Gall promoted phrenology around 1800, claiming that separate mental 'faculties' such as ambition or destructiveness could be judged from bumps on the skull. Phrenology failed under scrutiny: its claims rested on selected cases matched to skull features rather than on controlled, reproducible tests. Its lasting contribution was the idea of localisation of function.

Pierre Flourens studied brain function experimentally in the 1820s by removing (ablating) parts of animal brains, mainly in birds, and observing behaviour; damage to the cerebellum, for example, disrupted coordinated movement, although he concluded that the cerebral hemispheres worked as a whole rather than as separate faculties. In the twentieth century the neurosurgeon Wilder Penfield electrically stimulated the exposed cortex of conscious patients during epilepsy surgery, mapping sites that produced movements, sensations and sometimes memory-like experiences.

These methods produced valuable knowledge, but it was gained through risky and invasive practices: animals were harmed and surgical patients faced real danger. Modern research ethics require informed consent, minimisation of harm and strong justification for any animal research.