biological approach

• biological approach assumptions:

  • all behaviour has a biological origin
  • they look at the biological structures and processes such as genes, neurochemistry and the nervous system to understand behaviour
  • brain structure and function can explain our thoughts and behaviour (opposite of behaviourists)
  • thoughts, feelings and behaviour have a physical basis
• natural selection and evolution:

  characteristics not suited to a specific environment will die out, as it struggles to survive. With time, it will evolve so that only adaptive characteristics remain in future offspring.

  • charles darwin
  • no one decides which characterises are advantageous but the possessive of the such characteristics are most likely to survive.
• how does evolution and natural selection explain human behaviour?

  behaviours such as aggression would have made it more likely for our ancestors to survive and pass on genes. This means aggression has an adaptive purpose because it facilitates survival and adaptation to the environment.
• genes:

  definition:

  a genetic information carried by DNA in chromosomes, found within a cells‘ nucleus

  • they are passed on through generations of a species if they survive and successfully reproduce.
  • genes form a basis of behaviour and they are heritable
• what did behaviour geneticists study?

  whether behavioural characteristics are inherited in the same way as physical characteristics e.g intelligence
• study of monozygotic twins:

  why?

  to see if behavioural characteristics has a genetic basis

  • monozygotic twins are found to have the same musical ability than dizygotic twins - suggesting genetic ability
  • monozygotic twins share 100% of DNA
  • can compare concordance rates between pairs of twins
• what is a concordance rate?

  the percentage of pairs of twins or other blood relatives who exhibit the same trait or disorder (purely biological - mz twins rate is 100%)
• what are monozygotic twins:

  identical twins
• what are dizygotic twins?

  non-identical twins
• genotype:


  a persons genetic makeup

  monozygotic twins have the same genotype
• phenotype:

  the way genes are expressed through physical, behavioural and psychological characteristics (what you see)
• monozygotic twins - phenotype and genotype

  • expression of a genotype is influenced by environmental factors
  • despite having the same genes, the way the twins are expressed (phenotype) is different e.g by dying-hair
  • human behaviour depends on interactions between inherited factors and environment
• effects on brain physiology:

  interactions between regions of the brain help to control different functions, which biological psychologists assume to be significant in determining our actions
• effects on brain physiology:

  beige = frontal lobe

  • conscious awareness
  • planning decision making

  blue= parietal lobe

  • associated with processing of sensory info

  green = occipital lobe

  • associated with visual perception

  pink = temporal lobe

  • understanding language

  
• What is the genotype for tooth decay in identical twins?

  The genotype for tooth decay is the same for all the twin pairs.
• Why would identical twins be expected to have the same tooth decay pattern?


  Because they are all MZ/identical twins.
• What does it indicate if some twin pairs have different tooth decay outcomes?

  It indicates that their phenotypes differ and other factors affected tooth decay.
• What are some factors other than genes that could affect tooth decay in twins?


  Diet and brushing teeth are examples of factors that could affect tooth decay.
• case study

  • case of Phineas Gage
  • study demonstrates the influence of a biological structure (fronta—cortex) on behaviour
  • he became antisocial and personality changed- became rude
  • part of his frontal cortex was destroyed by a metal rod
• effects on neurochemistry (impulses):


  electrical impulses enable internal communication that directs our behaviour, travelling around the brain to/from the body

  • impulses are transmitted between neurons at synapses, junctions where neurotransmitters are released that inhibit or excite other neurons to achieve different responses
• effects on neurochemistry (neurochemical imbalances):

  hormones influence our behaviour

  • Carre-et-al found that high levels of testosterone are associated with defensiveness and territoriality in a study investigating ice hockey players
  • neurochemical imbalances in the brain are often associated with abnormal behaviour e.g imbalances of dopamine are associated with mood disorders like depression