the biological approach

what does the biological approach assume?

everything psychological is firstly biological

what methods of investigating the genetic basis of behaviour are there?

• twin studies

• family studies

• adoption studies

• selective breeding

what are genes?

the basic physical and functional unit of heredity that are inherited from one generation to the next and carry instructions for characteristics

what are monozygotic twins?

twins that are formed when a fertilised cell splits into two - identical

what are dizygotic twins?

twins that are formed when two separate eggs are fertilised - fraternal

what are concordance rates?

the extent to which a pair of twins share similar traits or characteristics

what is a genotype?

the genetic code in the DNA

what is a phenotype?

the physical appearance that results from the genotype

what do phenotypes depend on?

the interaction of genetic and environmental factors

what do phenotypes determine?

an individual’s ability to reproduce and survive

what is a recessive gene?

a gene that only shows if the individual has two copies of it

what is a dominant gene?

a gene that always shows, even if the individual only has one copy

what is the nervous system made up of?

• the cns

• the pns

• neurons

what does the central nervous system consist of?

the brain and the spinal cord

what does the peripheral nervous system consist of?

the somatic (physical) and autonomic nervous systems

what do neurons do?

transmit nerve impulses in the form of electrical signals

what are neurons?

individual nerve cells

what is evolution?

the changes in inherited characteristics in a biological population over successive generations

what did charles darwin emphasise in regards to evolution and behaviour?

• natural selection

• sexual selection

what is natural selection?

animals with particular traits that provide them with advantages to aid their survival live to reproduce and pass on the adaptive traits

what is sexual selection?

males have an abundance of sperm whereas females have 1 egg per month and a gestation period of 9 months so females tend to be more particular when choosing mates

when are neurotransmitters released?

when a nerve impulse reaches the end of one neuron

what are the types of neurotransmitters?

• excitatory neurotransmitters

• inhibitory neurotransmitters

what are excitatory neurotransmitters?

they trigger nerve impulses in the receiving neuron and stimulate the brain into action e.g., dopamine

what are inhibitory neurotransmitters?

they inhibit nerve impulses to calm the brain and balance mood e.g., serotonin

what are the frontal lobes involved with?

functions such as speech, thought and learning

what do the parietal lobes process?

sensory information such as touch, temperature and pain

what are the temporal lobes involved with?

hearing and memory

what do the occipital lobes process?

visual information

what are hormones?

chemicals that are produced by endocrine glands which together make up the endocrine system

what do hormones respond to?

signals from the brain

where are the hormones secreted into?

directly into the bloodstream and travel to target cells

how do hormones exert their influence?

by stimulating receptors on the surface or inside cells

what are the strengths of the biological approach?

• RWA - success of drug treatment e.g., SSRIs for OCD - family history is a reliable predictor for disease risk

• twin studies use large samples - e.g., Bouchard studied heritability of IQ - 1500 pairs of twins + 350 adopted/bio siblings - correlation of 0.9 for MZ twins - quantitative data - high in reliability

what are the weaknesses of the biological approach?

• biological determinism - complex human behaviour is not genetics alone - simplistic - ignores environmental influence - people are capable of sophisticated cognitive processing - limited external validity

• well-known twin studies conducted before the use of DNA testing - DZ twins may have been incorrectly labelled MZ - must determine zygosity - question veracity of status damages validity of findings