🧠 The Role of Animal Research in Understanding Human Behaviour (HL Only)

📌Key terms

Term	Definition
Animal Research	The scientific use of non-human animals to investigate biological and psychological processes relevant to human behaviour.
Translational Research	Research using animal models to understand mechanisms that can be applied to human conditions (e.g., stress, learning, memory).
Comparative Psychology	The study of similarities and differences in behaviour across species to infer evolutionary and biological principles.
Ethological Validity	The extent to which animal research reflects natural animal behaviour, ensuring ecological accuracy.
3Rs Principle	Ethical framework for animal research — Replacement, Reduction, Refinement.
Extrapolation	Applying results from animal studies to humans, assuming shared biological mechanisms.
Lesion Studies	Intentional damage or stimulation of specific brain areas in animals to study behaviour changes.
Enrichment	Providing stimulating environments for laboratory animals to enhance well-being and validity.

📌Key Studies

Rosenzweig, Bennett, & Diamond (1972)

• Aim: Investigate whether environmental factors (enriched or deprived) affect neuroplasticity in the cerebral cortex of rats.
• Method: Rats were placed in enriched or deprived conditions for 30–60 days; cortical thickness measured post-mortem.
• Findings: Enriched environment rats had thicker cortices and higher acetylcholinesterase activity.
• Conclusion: Stimulation influences synaptic growth — demonstrating neuroplasticity.
• Evaluation:
  • ✅ Strengths: Controlled lab design; replicable; established cause–effect link.
  • ⚠️ Limitations: Limited generalizability; ethical concern over euthanasia.

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2. Rogers & Kesner (2003)

• Aim: Examine acetylcholine’s role in spatial memory using rats.
• Method: Rats trained to find food in a maze; injected with scopolamine (ACh blocker).
• Findings: Scopolamine group took longer and made more errors.
• Conclusion: Acetylcholine is essential for memory formation.
• Evaluation:
  • ✅ Strength: Demonstrated neurotransmitter function under controlled conditions.
  • ⚠️ Limitation: Translational gap — human cognition is more complex.

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3. Sapolsky (1990s–2005)

• Aim: Investigate stress physiology in wild baboons to model human stress responses.
• Findings: Dominance hierarchies affected cortisol levels; low-ranking baboons had chronically high cortisol, paralleling human stress-related disorders.
• Evaluation:
  • ✅ Strength: Naturalistic validity; long-term field observation.
  • ⚠️ Limitation: Causality unclear; ethical concerns over observation of suffering.

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4. Harlow (1958)

• Aim: Study the importance of comfort contact in attachment.
• Method: Infant rhesus monkeys given wire or cloth “mothers.”
• Findings: Monkeys preferred soft cloth mothers, even without food.
• Conclusion: Attachment is based on comfort, not feeding.
• Evaluation:
  • ✅ Strength: Groundbreaking insight into emotional bonding.
  • ⚠️ Limitation: Severe psychological harm; modern ethics would not approve.

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5. Martinez & Kesner (1991)

⚠️ Limitation: Extrapolation to humans limited.

Aim: Determine the role of acetylcholine in memory formation in rats.

Method: Rats injected with scopolamine or physostigmine (ACh enhancer) before maze learning.

Findings: Scopolamine impaired, while physostigmine improved memory.

Conclusion: ACh crucial for encoding memory.

Evaluation:

✅ Strength: Controlled and replicable; biological mechanism clarified.