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IB DP Psychology — Biological Approach | SL & HL | Paper 1
🎯 Learning Intentions By the end of this note, you will be able to:
- Define animal research and biological reductionism using IB-aligned terminology.
- Explain the rationale for using animal models in psychological research and the conditions under which findings can be generalised to humans.
- Describe the role of evolutionary continuity in justifying animal research within the biological approach.
- Evaluate research evidence for and against animal research and biological reductionism using supporting and opposing studies in ACAS format.
- Apply concepts of animal research and reductionism to a real-world case study from the biological perspective.
- Discuss the extent to which biological reductionism provides a complete explanation of human behaviour.
- Analyse animal research and reductionism using relevant concept areas: Bias, Causality, Perspective, and Responsibility.
Introduction & Context
Imagine a scientist wants to understand how stress affects memory. Ethically, they cannot surgically alter a human brain, keep a person in a controlled cage, or deliberately expose them to extreme fear over weeks. Yet these are precisely the kinds of controlled conditions that would allow researchers to isolate biological causes of behaviour with precision. This tension — between what we want to know and what we are permitted to do — is one of the central reasons psychologists have historically turned to animals as research subjects.
Animals share a surprising amount of biological machinery with humans. Our neurons fire in the same way, our stress hormones follow the same pathways, and our brains share ancient structures that evolved hundreds of millions of years ago. This biological overlap is not coincidental — it is the product of shared evolutionary history. The biological approach in psychology takes this overlap seriously, arguing that studying simpler organisms can illuminate the mechanisms underlying human thought, emotion, and behaviour. But this raises a deeper question: if we reduce human experience to biology, and then reduce that biology to findings from rats or monkeys, how much of the human story are we actually telling?
🔍 Analogy — The Blueprint Argument Think of the human brain as a skyscraper and the rat brain as a small house. They are built from the same materials — bricks, steel, wiring — and follow the same architectural principles. A structural engineer studying how houses respond to earthquakes can learn a great deal about skyscrapers, even though the buildings are very different in scale and complexity. Animal research works on the same logic: shared biological "materials" mean findings can transfer across species, even if the full structure differs enormously.
Core Concepts
Before we can evaluate whether animal research is useful or whether biological reductionism is justified, we need to understand what each of these ideas actually claims. They are related but distinct: animal research is a methodological choice, while biological reductionism is a philosophical position about how behaviour should be explained. Understanding the difference between them — and how they interact — is essential for exam answers.
When psychologists study behaviour, they face a fundamental problem: the most informative experiments are often the ones that cannot ethically be conducted on humans. Researchers cannot randomly assign people to experience childhood deprivation, cannot implant electrodes in living human brains without medical necessity, and cannot breed humans selectively to study genetic effects. Animals, however, can be