The Biological Approach: An Overview
The biological approach explains behaviour by looking at the body's physical systems: the brain, the nervous system, hormones, and genes. It assumes that psychological events have biological causes, and that studying those causes rigorously can explain why people think, feel, and act as they do.
This approach is powerful because it is precise and measurable. Brain scans, genetic studies, and controlled experiments with chemical messengers have produced treatments that genuinely help people. At the same time, the approach raises hard questions about how much a biological explanation can ever fully capture human behaviour, and whether reducing a person to their neurotransmitters or genes risks missing something important.
The concepts running through this subtopic are causality (does biology cause behaviour, or is the relationship more complex?), reductionism (what is gained and lost by explaining behaviour at the biological level?), and measurement (how do we know what is happening inside a living brain?). Keep these in mind as you work through each section.
Animal Research and Animal Models
Research conducted using non-human animals to investigate biological, psychological, or behavioural phenomena, typically used when equivalent human studies would be impractical or unethical.
Animal research has two overlapping purposes in psychology. First, it allows researchers to manipulate variables that cannot be manipulated in humans, such as lesioning specific brain regions or injecting neuroactive substances. Second, animal models are used to represent human conditions, chosen because the species shares relevant biological features with us.
Why animals are used:
- Some experiments are too invasive or dangerous to conduct on humans.
- Controlled laboratory conditions allow researchers to isolate variables and make stronger causal claims.
- Many species, especially rodents, share enough neurological similarity with humans to make findings informative.
- Shorter life cycles in most laboratory animals make heredity and developmental research more feasible.
Key ethical framework: the 3 Rs
The guidelines most widely applied to animal research require researchers to address three principles:
- Replacement: use non-animal alternatives wherever possible.
- Reduction: use the minimum number of animals needed to produce meaningful results.
- Refinement: design the study to minimise suffering and focus on achievable aims.
Martinez and Kesner (1991) used rats to investigate the role of acetylcholine (ACh) in spatial memory.
Rats were injected with one of three substances: scopolamine (an ACh antagonist, which blocks ACh activity), physostigmine (an ACh agonist, which enhances ACh activity), or a placebo.
All rats then completed a maze. Rats given scopolamine made significantly more errors; rats given physostigmine made fewer. The researchers concluded that ACh facilitates spatial memory.
This study would have been impossible to conduct on humans in the same form, illustrating the practical value of animal models.
Strengths of animal research:
- Precise experimental control enables causal conclusions that correlational human studies cannot support.
- Findings have directly informed the development of psychiatric medications and neuroprotective treatments.
- Ethical guidelines such as the 3 Rs provide a framework for justifying and regulating use.
Limitations of animal research:
- Generalisability is limited by biological and cognitive differences between species. Rats do not have the cultural or linguistic complexity of humans.
- Ethical concerns remain even under the 3 Rs framework; animal welfare is a genuine moral question, not just a procedural one.
- A focus on biological variables can leave out the social and environmental context that shapes human behaviour.