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 ** 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= ** 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
Strengths:
- MZ and DZ twins share same enviro. = natural control of enviro. effects
- only MZ twins share all DNA = test influence of genes
Weaknesses:
- 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
Strengths:
- control enviroment influences = different environment to bio. parents= similarties of bio. parents genetic
- longtiduinal studies =development trends over years
Weaknesses:
- 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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