Biological Approach Part 2
- Created by: Beth
- Created on: 10-04-14 15:40
Methodology - Evaluation of Animal Studies (rats)
When and why?
- trial drugs
- high control over factors
- easy and cheap to keep
- similar evolutionary past to humans
- test hypothesis not ethical on humans (brain lesions, sex hormones
Credibility?
- trustworthy? believe? likelihood?
- yes - hormones same effect on humans and rats
- no - baby development different - humans more complex
Methodology - Evaluation of Animal Studies (rats)
Generalisability?
- low
- different cognitively and emotionally
- brains different - humans larger prefrontal cortex
- different behaviour - shaped by different social norms
Pratical reasons?
- genetic engineering - unethical in humans
- allow 'minimal' pain and distress - not in humans
- size - small and easily kept
- short pregnancy - study generations of genes quickly
Methodology - Evaluation of Animal Studies (rats)
BPS guidelines and ethics;
- legislation to protect
- suitable species choice
- number limited - no wastage
- procdures - minimalise pain
- procurement - reputable supplier
- suitable housing and care
- another purpose - breeding or experiment
Bateson's cube;
- animal suffering
- medical benifit
- quality of research - not guaranteed untl after
- only proceed if missing block
Practical - Spatial Awareness - description
Aim: To see if there is a difference between males and females when solving a mental shape rotation task, which represents a spatial awareness task, with males solving it quicker than females
Method:
- lab experiment
- oppurtunity sampling
- 20 participants (10 male, 10 female)
- independent measures
- IV = gender DV= time to complete spatial awareness task
- alternative hypothesis (directional) = males perform quicker at s.a. task than females
- null hypothesis = no difference males at time taken to complete s.a. task
- non directional hypothesis = no difference
Practical - Spatial Awareness - description
Procedure:
- P. chosen and fully informed, not spoil test
- P. taken seperate room to do test individually
- Researcher reads instruction to p. and ask if agree, before do test on computer. DV = time taken
- P. debriefed check if can use data
- Researcher only records gender and time, prove to p.
Equipment:
- data sheet
- standardised instructions
- mental shape rotation task on computer, providing average time in sec.
Practical - Spatial Awareness - description
Results:
- male mean score = 2.74
- female mean score = 4.12
- observed value U=34
Conclusion:
Observed value of U=34 is above critical value of 27 and so result is not significant, therefore I must accept null hypothesis " there will be no difference between males and females, with time taken to complete spatial awareness task"
Practical - Spatial Awareness - evaluation
Generalisability:
- oppurtunity sampling - not representative of target population - based on gender, not account for age or ability
Reliablilty:
- lab environment - high control of extraneous variables - more replicable
- standardised procedure - reliable
Application:
- careers - but sexism
Validity:
- low ecological - lab experiment - artificial environment
- computer test - artifical task - not real life scenario
Practical - Spatial Awareness - evaluation
Ethics:
- all BPS guidelines followed - no issues
- brief, debrief, informed consent, confidentiality
Objectivity:
- measurement of time - free from bias - no opinion
Statistics
Inferential stats = how much due to chance?
descriptive stats = measurements of central tendency = mean, median, mode
Levels of measurements:
- interval = real measurements
- ordinal = ranks
- nominal = categories
Experiment (difference) = indpendent measures = interval = Mann Whitney U = or nominal = Chi squared
Correlation (2 measures) = ordinal = Spearman's
Statistics (Mann Whitney U)
- Observed value = result you found
- Critical value = table of significance
- significance = below critical value
- o.v less c.v accept alternative hypothesis
- o.v higher c.v accept null hypothesis
p <= 0.05
p probability of results due to chance
< = less than or equal to
0.05 5% (chance)
Detail study - Money - David Reimer (Ablatio Penis
Aim:
- encourage the Reimer's to let their twins (Bruce & Brian) be part of experiment
- Bruce brought up as female after circumcision accident, left no penis, easier for reconstruction surgery
- prove nurture overide nature
Case description:
- Mother and twins visited Money often for 9 years to report on developments
- mother most because put most effort unto Bruce becoming Brenda
Case analysis by Money (results) :
- success, Brenda showed gender appropriate beahviour ;dresses, dolls and happy
Detail study- Money - David Reimer (Ablatio Penis)
Conclusion (Money's):
- can go against nature
- nurture stronger with small interventions (surgery)
- Brenda happier as girl
Real Analysis (results):
- 13 yrs Brenda masculine and suicidal
- 15 yrs mother against Money tells of change
- Brenda becomes David
- David reconstructive surgery, marry, stepkids and 'male' job
- 30 yrs depressed, divorced, no job
- 2002 Brian (twin) drug o.d. - belief over case
- 2004 David suicides
Detail study -Money -David Reimer (Ablatio Penis)
Real conclusion:
- Nature stonger than nurture - felt wrong to be girl - changed back to natural gender
Detail study-Money -David Reimer (Ablatio Penis)
Generalisability:
- low
- one off study and unique case - not g. other situations
Reliability:
- unethical if repeat - unkown reliabilty
- support of Reiner & Gaerhart study - majority females convert back - reliable
- against of Daphne West - not reliable
Application:
- childhood transgender ops, only when child decides
- nature more determinate of gender than nurture
Detail study-Money -David Reimer (Ablatio Penis)
Validity:
- no procedure controls - case study - no unnatural criticisms- eco. valid
Ethics:
- no consent
- no right to withdraw
- parental mpermission of brief and informed consent
Detail study-Raine-Murderers brains PET
Aim:
- to use PET measure brain acticity in areas associated with violence, in murderers and non-murderers
Procedure:
- 2 groups - 41 murderers plead not guilty reason insanity - matched control group 41 non-murderers on age, sex and schizophrenia
- all injected glucose and rodioactive tracer, reveal active areas - absorb glucose
- p. continuous performance task (CPT) detect signals 32 mins
- finish task immediate PET scan show levels of activity in areas
Detail study-Raine- Murderers brains PET
Results:
- m. less active prefrontal cortex - low control and violence
- m. less active left angular gyrus and bilateral superior gyrus (parietal cortex) - low verbal ability - poor education and compensation of crime
- m. less active corpus callosum - low self control - can't control violent impulses
- m. abnormal limbic system - emotion expression
- m. less active amygdala and hippocampus (left)
- m. more active thalamus (right)
- = fearlessness - lack understanding negative efects of violent behaviour
Conclusion: violence and agression biological not environmental
Detail study-Raine-Murderers brains PET
Generalisability:
- 41 p. each group - large - matched - confident in result of difference
- no circumstances for murders or others who agressive but not murderers
- only murderers - no other violent criminals
Reliability:
- repeat other groups - strengthen results
- results cannot conclude biolongy only cause (e.g. environmental trigger)
- compare to Raine's Anti-social Personality Disorder study results - small prefrontal cotex
Application:
- PET scans evidence in court when plead NGBRI
Detail study-Raine-Murderers brains
Validity:
- PET results not precise on area or activity
- not why active
- not tell which - abnormalities causes violence or violence causes abnormalities
Ethics:
- no protection - stress of PET scan
Key Issue - Are transgender ops. ethical? Describ
What are transgender ops?
- aim of channging the physical sex of person
Why would someone want a transgender op?
- choice of patient - transsexuals
- infancy identity - indiscriminate sex organs - hermaphrotidism
Why are transgender ops a society issue?
- ethics of changing gender by surgery - especially children, no consent
- surgery permanent and irreversible - consider carefully
Key Issue - Are transgender ops. ethical? Evaluate
For:
- surgery sucess - new parts develop and function need done early infancy
- reactions of others - ethics of changing child to 'normal' so others accept better than maintain original
Against:
- consent - adult informed risks and give consent - child not consent to life altering surgical procedure - parents and Dr decision not fit childs feelings later
- surgery decisions - choice of gender - driven surgeon - female genitals easier to create and function
Key Issue- Are transgender ops. ethical?
Against:
- David Reimer case - raised female and op. as penis construction surgery limited- biology overided and felt more masculine - other reactions caused low self esteem - depression and suicide - ethic problems
- Reiner & Gaerhart - 16 males born small or no penis but normal testes- 14 raised female but all identiftied some point gender identity issues - most of 14 later chose male identity and lives from teenagers - 2 males raised males always identified as male despite abnormalities
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