The biological approach

• Assumption 1 of the biological approach

  Behaviour can be explained in terms of evolutionary influences
• Evolutionary influences


  • To evolve means to change with time over many generations
  • In psychology Darwin's theory of evolution has been used to explain how human behaviour has changed over millions of years so that it has adapted to the demands of individual environments
• Theory of adaptiveness


  • Based on Darwin's theory of natural selection
  • Any genetically determined behaviour that enhances an individuals' chance of survival and reproduction will be passed on to the next generation
  • Natural selection takes place at the level of your genes
• Localisation of brain function


  • Different areas of the brain regulate different functions
  • The cerebral cortex is the outer area that covers the surface of the brain and is divided into four lobes: frontal, occipital, parietal, and temporal
  • Each lobe has a different function
• Functions of brain lobes

  • Frontal lobe regulates personality
  • Occipital lobe regulates vision
  • Parietal lobe receives sensory information
  • Temporal lobe processes memory and auditory information
• An example of neurotransmitters in psychology is...

  Neurotransmitters and Mental Health: Neurotransmitters play a significant role in mental health. For example serotonin regulates mood, sleep and appetite. Too little serotonin has been found in people suffering from depression. Some antidepressants medications work by increasing the availability of serotonin at postsynaptic receptor sites. High levels of the neurotransmitter dopamine have been associated with symptoms of schizophrenia. Drugs that block dopamine activity have been found to reduce symptoms of schizophrenia.
• Evolutionary influences in psychology

  • Biological Preparedness
• Biological Preparedness


  Evolutionary psychology suggests certain fears are adaptive behaviours that helped our ancestors to survive
• Biological Preparedness


  • Inherited predisposition to fear certain types of animals, such as snakes
• Fears linked to biological preparedness

  • Predatory animals
  • Animals associated with disgust
• Fears of predatory animals and animals associated with disgust


  Naturally elicited fear in humans
• This is an example of evolution for survival purposes
• Nervous system

  • Made up of interconnected cells called neurons
  • Brain contains billions of neurons
  • Neurons have branches called dendrites
  • Dendrites give neurons flexibility to connect with other neurons
• Neuron communication

  1. Neurons communicate at the synapse

  2. With chemical messengers called neurotransmitters

  3. Neurotransmitters released from presynaptic vesicles

  4. Neurotransmitters either stimulate or inhibit receptor sites in other neurons
• Types of neurotransmitters

  • Dopamine (associated with rewards and schizophrenia)
  • Serotonin (associated with arousal and depression)
  • Adrenaline (associated with arousal)