AS Psychology Biological Approach

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  • Created by: Beth
  • Created on: 07-03-14 13:16

Definition of Approach

  • The bilogical approach can explain human behaviour through the influence of individual differences of the nervous sytem and genes
  • DNA make genes, which can be found in the 23 chromosomes we inherit from each parent. They determine physical looks and behviour inherited from family. 
  • The CNS (Central Nervous System) is made up of the brain and spinal chord. Behaviour is individual because of the way the CNSinterprets signals sent and recieved form/ to it. 
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Assumption 1 CNS

  • Neurons are special type of cell that carries electircal impulses.
  • They send signals to between each other using neurotransmitters.
  • Neurotransmitters are sent across synaptic gap
  • Dendrite receives impulse, impulse goes through cell body, axon, neurotransmitter across synaptic gap, receptor (lock and key- impulse only continues if neurotransmitter fits)
  • CNS spinal chord is made up of thick bundle of nerves going down the spine. These branch out and again until individual nerves branch out to reach different body parts
  • CNs is communication network, the brain sends and recieves signals through network of nerves
  • Some nerves are to brain others from brain
  • drugs affect the way nerves work, resulting in loss of control of the body
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Assumption 2 Genetic Influences

  • We inherit 23 chromosomes from each parent
  • Chromosomes contain genes that determine looks and behaviour
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Assumption 3 - Hormones

  • hormones are chemicals released into bloodstream and change a body function
  • Pituitary gland releases hromones like testosterone and oestrogen 
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Assumption 4 - Brain lateralisation

  • specific area of brain for specific function
  • difference in lateralisation between males and females
  • hippocampus - memory - london cab drivers - damage like Clive Wearing
  • Corpus callosum - connects hemispheres - bundle of neurons - females larger
  • hypothalamus - sends signals to pituitary gland
  • brain stem - connects brain to spinal chord
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Nature vs. Nurture

  • Nature = biological =inherited characteristics causes behaviour
  • Nurture = environment
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Explanation of gender development description

Assumption 1 - Genetic influences

  • all fouetes same undeveloped sex organs
  • original system could develop into either male or female sex organs
  • 6 to 8 weeks gonads start developing, potential to become either testes or ovaries
  • chromosomes determine sex. If XX female. If XY male.
  • SRY gene attached to Y chromosome produces protein TDF (Testes Determining Factor)
  • TDF influences development of gonads- to become testes
  • females no Y chromosome - no SRY - no TDF- default mode- deveopment of gonads to become ovaries
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Explanation of gender development description

Assumption 2 - Hormones

  • 8 to 12 weeks  differentiation of external genitalia determined by presence/absence of male hormones
  • male hormones= androgens= e.g. testosterone
  • 6-8 weeks protein hormone HY-antigen released if Y chromosome
  • encourages development of testes whilst stopping ovary development
  • Testes release anit-mullerian hormone (MIS) stops ovary development
  • testes produce androgens = stimulates development of full male sex organs
  • 3 months prenatal development Wolffian system develop into full male sex organs
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Explanation of gender development description

Assumption 2 - Hormones cont.

  • absence of androgens
  • no HY antigen and no MIS
  • gonads development into ovaries
  • Mullerian system develop female sex organs
  • puberty = secondary sexual characteristics = x2 e.g.
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Explanation of gender development description

Assumption 3 - Brain lateralisation

  • if testosterone present = hypothalamus signals for pituritary gland to release more male hormones
  • if more oestrogen = hypothalamus signals for pituitary gland to release more female hormones
  • speech and comprehension - males left- females both - men more effected by stroke as lateralised brain
  • spatial awareness - males right - females both
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Explanation of gender development evaluation

 For: supporting research

  • David Reimer - born XY and male- circumcision accident burnt off penis - raised female - behaviour more masculine- surgery to turn back male - biology (nature) hormones stronger than  upbringing (nurture) - genetics stronger 
  • Reiner & Gaerhart - 14/16 males raised females because of no or small penis but XY and testes but later chose to live as male - nature stronger even with surgery 
  • Dorner rat studies- destroyed sex centres of male rats brains and behaviour female - female rats injected male hormones act male - hormones large control over biology giving us gender 
  • Pfier's rat studies - removed sex organs-male rats acted female- transplant testes on to female rats released male hormones - no testosterone gender default  female 
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Explanation of gender development evaluation

  •  Weakness of animal research - brains diferent - not human - not ethical on humans - quicker prenatal development (22 days)

For and against: Research = for hormones against genes

  • Batista family - mutant recessive gene caused born female genitalia but XY chromosome
  • Puberty surge tesosterone causd other male hormones lacked before birth
  • developed full male genitalia and adopted new gender
  • supports hormones control development of sex organs and genitals - surge cause to correct genitals to match chromosomes
  • against genetics - chromosmes (XY) automatically stimulate male hormones and male genitalia development
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Explanation of gender development evaluation

For and against supporting research: for hormones, against genetics

  • Pseudo-hermaphrodites = chromosomally one sex, physically appearance opposite sex and raised that way
  • androgenital syndorome= XX exposed too much androgens (male hormones) and so develop male genitals = e.g. Daphne Went
  • androgen insensitivity syndrome = XY lacks exposure of androgens and develop female genitals
  • support prenatal exposure to hormones determines gender development
  • against genetics, should automatically encourage correct hormone production
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Explanation of gender development evaluation

Research against:

  • Samoan Fafafinis = +2 gender roles = no girl then boy chosen to be raised female
  • Fafafinis do 'female' gender stereotypical role like housework but viewed more effective (i.e. strength)

Alternative theories:

  • Learning - get gender through operant conditioning and social learning
  • Psychodynamic - get gender by oepedius or electra complex, and unconcious influences
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Methodology -Twin Studies

1. MZ vs. DZ

Monozygotic twins

  • share 100% DNA
  • share same environment
  • high concordance rate [similarity] (intelligence 99%)

Dyzygotic twins

  • share 50% DNA
  • share same environment
  • low concordance rate (intelligence 10%)

Intelligence genetic?

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Methodology -Twin Studies

2. MZ vs. MZ reared apart

  • high concordance with MZ vs DZ could be because share same environment
  • sepearate nature and nurture by study 100% same DNA, 0% same environment
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Methodology -Twin Studies Evaluation


  • MZ and DZ twins share same enviro. = natural control of enviro. effects
  • only MZ twins share all DNA = test influence of genes


  • MZ treated more same than DZ (appearance more similar) = enviro. not as controlled
  • MZ same DNA but environmental influences switch genes on/off = epigenetic modification = become different
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Methodology -Adoption Studies

  • similarities between adopted child and adoptive parents = nurture = no shared genes = behaviour learnt
  • similarities between adopted child and biological parents = nature = share genes cause behaviour

e.g. language abiility

  • score closer to adopt. parents = learnt 
  • score closer to bio. parents = genetics and inheritance
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Methodology -Adoption Studies Evaluation


  • control enviroment influences = different environment to bio. parents= similarties of bio. parents genetic
  • longtiduinal studies =development trends over years


  • adopt. parents enviro. similar to bio. parents enviro. = not cause stress= no difference
  • adopt. parents all similar, causing results (e.g. care over language ability help)
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Methodology - Brain imaging/ scanning PET

  • scan = non-invasive imaging method of body and organs

PET scans (Positron Emmission Tomography)

  • measure brain function and activity
  • radioactive tracer injected into blood, breaks down and sensed
  • more active area, more radiation, more glucose used (energy)
  • dark, warm colours (red/orange) = high activity   
  • cool/light colours (blue/green) = less activity
  • e.g. Raine
  • cancer detection = red = cells lots energy for metabollic rate
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Methodology - Brain imaging/ scanning MRI

MRI (Magnetic Resonance Imaging)

  • measures brain structure
  • use magents not x-rays for image production
  • strength of magnetic field causes body atoms respond
  •  emissions detected and analyzed
  • create layers image
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