4.2.1c - Biological Approach

Monday 18th March ‘24

What are the key assumptions?

• Genetics - behaviour evolves the same way as physical characteristics through the process of evolutionary adaptation; examination of animals can be useful in tellung us about our own behaviour.

• CNS includes brain & spinal chord - brain is main focus when explaining behaviour as it is the origin of thought and understanding of the world.

• Biochemistry of body - neurotransmitters found in brain and hormones in body believed to impact human behaviour.

What does this suggest?

• The mind lives in the brain - meaning that all thoughts, feelings and behaviour ultimately have a physical basis.

• Everything psychological is first biological.

What do twin studies tell us?

• Genotype - all the genetic information which an organism contains.

• Phenotype - characteristics coded for by the genetic information; can be influenced by environment.

• Identical twins seperated at birth - both John and Alan have exactly the same genotype however their phenotype becomes different due to a variation in their environment; a twin being in a very impoverished environment may not reach their genetic poential so may not grow to be as tall.

What are some supporting evidences?

• Gottesman (1991) - schitzophrenia - concordance rate for MZ twins was 48% and 17% for DZ twins.

• Craddock & Jones (1999) - bipolar depression - concordance rate for MZ twins was 40% and 5-10% for DZ twins.

• Walters & Kendler (1991) - anorexia nervosa - concordance rate for MZ twins was 23% and 9% for DZ twins.

• Through the biological approach in psychology, the concordance rates in twin studies favours the nature argument in that additional DNA shared can be correlated with the prevelance of psychological disorders. This can be seen by Nestadt et al who found 68% concordance rate of OCD in monozygotic twins compared with 31% in dizygotic twins. From this, it can be suggested that genotype plays significant role, more than environmental factors.