The biological approach to understanding behaviour is largely an investigation into correlations. Do areas of the brain correlate with behaviour? When changes take place in the brain do changes take place in behaviour or is the reverse the case? Could an individual’s behaviour be predicted from their genes? Is human behaviour subject to natural selection?

The relationship between biology and behaviour is a complex one of mutual causality. The technology available to investigate this relationship is becoming ever more sophisticated, while the ethics of this line of inquiry are increasingly an area for public debate.

The biological approach to behaviour looks at:

• the brain and behaviour
• hormones and behaviour
• genetics and behaviour
• the role of animal research in understanding human behavior

Relevant to all the topics are:

• the contribution of research methods used in the biological approach to understanding human behaviour
• ethical considerations in the investigation of the biological approach to understanding human behaviour.

Approaches to Learning

Topic: The Brain and Behavior

• Techniques used to study the brain in relation to behaviour
  • The choice of techniques used to correlate the brain with behaviour is based on a variety of factors including opportunity, available technology and costs. An awareness of these limitations as well as the strengths of these different techniques is important when evaluating the contribution they have made to understanding behaviour.
• Localization
  • Students should understand the concept of localization and how the function of different parts of the brain is determined as well as the limitations of this model.
• Neuroplasticity
  • The development of neural networks through repetition and neural pruning is both genetic and subject to environmental influences. Neural networks can change developmentally, over time or after injury. This is termed neuroplasticity.
• Neurotransmitters and their effect on behaviour
  • The effect of neurotransmitters on human behaviour can be explained using an appropriate example. Neurotransmitters allow the impulse to cross a synapse (excitatory) or stop the impulse and prevent it from crossing a synapse (inhibitory). Neurotransmitters are themselves affected by agonists which amplify their effect and antagonists which reduce their effect. As a result, neurons working together can produce a large variety of effects resulting in a complex repertoire of behaviours. As a result any claim of cause and effect should be treated with caution.

Topic: Hormones and behaviour

• Hormones and behaviour
  • The effect of a hormone on human behaviour can be examined using one or more examples. Pheromones and behaviour There is increasing evidence that pheromones may play a role in human behaviour, however, none are conclusive. A discussion on the effect of pheromones on behaviour is a useful exercise in critical thinking

Topic: Genetics and behaviour

• Genes and behaviour
  • The evidence for links between genes and certain types of behaviour requires critical evaluation in the light of environmental factors.
• Genetic similarities
  • Genetic similarity is referred to as relatedness. The greater the genetic similarities between two individuals or a group of individuals the higher the degree of relatedness. An awareness of the degree of relatedness between MZ and DZ twins, siblings, parents and children, and parents and adopted children provides a critical perspective in evaluating twin or kinship studies.
• Evolutionary explanations for behaviour
  • If genes code for behaviour as well as physical traits, then behaviour is subject to evolutionary pressures in the same way that physical traits are subject to evolutionary pressures.

Topic: The role of animal research in understanding human behaviour

• For all three topics in the biological approach, and with reference to research studies, HL students should study the following.
  • The value of animal models in psychology research.
  • Whether animal research can provide insight into human behaviour.
  • Ethical considerations in animal research.