IB Psychology - Rosenzweig, Bennet, and Diamond (1972)

Aims

To investigate whether environmental factors such as a rich or an impoverished environment affect development of neurons in the cerebral cortex.

Methods

- Rats were placed in either an enriched environment (EC) or an impoverished condition (IC).

- EC: 10-12 rats in a cage provided with different stimulus objects to explore and play with. This group also received maze training.

- IC: each rat in an individual cage (isolation and no stimulation).

- The rats typically spent 30 to 60 days in their respective environments before they were killed so the researchers could study changes in brain anatomy.

Results

- The anatomy of the brain was different for rats in the EC and the IC.

- The brains of EC rats had increased thickness and higher weight of the cortex. EC rats had developed more acetylcholine receptors in the cerebral cortex (important neurotransmitter in learning and memory).

Conclusions

- The research challenged the belief that brain weight cannot change. This was an important finding

- Follow-up of this research indicated that just 2 hours a day in an enriched environment produced the same plastic changes in the brain as in rats that had been constantly in the EC condition. This shows that the brain can change and adapt to new situations.

- Since brain plasticity is assumed to follow the same pattern in animals and humans the implications of the study are that the human brain will also be affected by environmental factors such as intellectual and social stimulation

Strengths

- The experiment was a rigorously controlled laboratory experiment so it was possible to establish a cause-effect relationship.

Weaknesses

- The experiment used animal models and therefore it may be difficult to generalize to humans unless research with humans provides the same results

- Rats were sacrificed