Cognitions, emotions and behaviours are products of the anatomy and physiology of our nervous and endocrine systems. There are biological correlates of behaviour.

Martinez & Kesner (1991) – An experiment to determine the role of neurotransmitter acetylcholine on memory formation (in hippocampus) of mazes on rats. Rats were trained to go through a maze and receive food at the end. After, one group of rats was injected with scopolamine which blocks acetylcholine sites thus decreasing available acetylcholine, a second group of rats with physostigmine, which blocks production of cholinesterase that removes acetylcholine from synapse and return neuron to resting state and the control group was injected nothing. The group injected scopolamine was slower finding their way around maze than the other two groups, and the group injected with physostigmine ran through the maze and made less errors. This shows that neurotransmitter acetylcholine plays an important role in memory formation.

Evaluation: use of experimental method with a control group made it possible to establish a cause-and-effect relationship between levels of acetylcholine and memory. It is questionable to what extent can this be applied to humans à shown that those with Alzheimer’s disease have damaged acetylcholine-producing cells. The experiment was harmful for rats.


Kasamatsu & Hirai (1999) – the aim was to investigate how sensory deprivation affects the brain. A group of Buddhist monks went on a 72-hour pilgrimage to a mountain where the didn’t eat, drink, speak… After 48 hours they began to have hallucinations, seeing ancestors etc. The researchers took blood samples before and after the monks reported having hallucinations. Serotonin levels increased in their brain, activating hypothalamus and frontal cortex, resulting in hallucinations. Serotonin is responsible for sleep, arousal levels and emotion.

Evaluation: criticism of reducing explanation of behaviour on neurotransmitters alone à reductionist. However, cause-and-effect relationship is uncertain; maybe hallucinations triggered release of serotonin. It cannot be generalised, because monks are a distinctive group.

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