the biological approach

• what is the biological approach

  • biological psychologists explain all aspects of psychological functioning in terms of physical factors within the body
  • they also consider the influence of evolution on behaviour
• physical factors within the body

  • genes
  • biological structures
  • neurochemistry
• the influence of genes on behaviour

  • behavioural geneticists study whether psychological traits such as intelligence and personality are inherited in the same way as physical traits
• what are twin studies used to investigate

  the influence of genes on behaviour
• what happens in a twin study

  • pairs are studied to see whether they are concordant for a particular trait
• types of twins

  • Monozygotic twins - share 100% of their genes - if MZ twins are more concordant for a particular trait we assume this is due to genetic factors
  • Dizygotic twins - share 50% of their jeans
• what is a genotype

  • genetic make-up of an individual
  • particular set of genes that an individual possesses
• what is a phenotype

  • observable characteristics of an individual - it is the way in which an individuals genes are expressed
  • influenced by environmental factors
  • this is why many psychologists accept that much of human behaviour upon an interaction between genes and the environment
• biological structures that influence behaviour include

  • the nervous system
  • the brain
• what is the the nervous system

  • specialised network of cells in the human body
• what is the function of the nervous system

  • enable communication between all parts of the body
• 2 sub sections of the nervous system

  • CNS
  • PNS
• PNS

  • carries information to and from the CNS
  • made up of SNS - governs voluntary actions
  • made up of ANS - which governs involuntary bodily functions
• what do neurons do

  • transmit electrical impulses - action potentials to provide the nervous system with its primary means of communication
• the brain

  • cerebrum is the largest part of the brain
  • split into 2 cerebral hemispheres - connected by the corpus callosum
• 4 cerebral hemisphere lobes

  • frontal lobe - involved in speech, learning and thought
  • temporal lobe - involved in hearing and memory
  • parietal lobe - involved in touch and taste
  • occipital lobe - involved in vision
• charles Darwin argues...

  • over time biological organisms become adapted to their environment through evolution
• evolution

  • the changes that take place in the characteristics of a population over time
  • mechanism behind evolution is natural selection
• theory of natural selection

  • variation exists within a species due to mutation
  • certain variations give an advantage
  • individuals who possess these variations are more likely to survive and reproduce
  • offspring will acquire these variations
  • these variations will become more widespread within the population
• what is behaviour influenced by - neurochemistry


  chemicals called neurotransmitters
• what do neurotransmitters do

  • act as messengers to transmit electrical impulses from one neuron to another across a gap between adjacent neurons - synapse
• imbalance in neurotransmitter....

  • linked to psychological disorders
  • e.g imbalance in dopamine - symptoms of schizophrenia