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Bio. approach to aggression ..individ. genetic makeup --> MZ twins share ALL of their genes, DZ 50% --> Research conducted to est. a concordance b/twn twins for aggress. traits --> If results show MZ twins more similar in terms of given trait then it could be due to having identical genetics --> COCCARO: 50% variance in aggression could be attributed to genetic factors

Adoption studies used study genetics in aggress. --> If +ve correlation b/twn aggress. in adopted children & bio. parents then genetic effect implied but if +ve correlation found in adopted children & adopted parents then environmental effect --> HUTCHINGS: 14000 adoptions DENMARK .. adopted boys w/criminal convictions had bio. fathers w/criminal convictions --> H/W not all criminal convictions are violent or aggressive (e.g. fraud, speeding etc) & not all aggressive acts result in criminal conviction --> METHODOLOGY: large sample reduced effects individ. diff. & increases generalisability --> Does not provide substantial evidence of concordance rates, based on results from denmark, not necessarily applicable to other cultures & countries --> historical validity - 1975 since then improvements in scientific technology (brain scanning etc) - argued section of brain linked to aggression 

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genetic factors II

No individ. gene for aggression has been identified but gene that produces MAOA been associated w/aggress. since moderates effects of serotonin .. low levs. of serotonin = aggress. --> BRUNER Dutch family: male members violent & aggressive.. involved in serious crimes of violence --> All had abnormal low levs. MAOA & defect in gene --> H/W case study..small sample..generalisability --> REDUCTIONISM: assumes  genetic mechanism alone cause aggressive behaviour h/w signif. research take behavioural factors into consideration - Bandura's study w/Bobo dolls .. aggression learnt from family members rather than genetics

2nd study CASPI: 500 male children --> low levs. MAOA more likely anti-social behav. but only if maltreated as children--> those high levs. MAOA & who were mistreated or those w/low levs NOT mistreated didnt display anti-social ---> Shows it is interaction b/twn genes & environment that determines behav. such as aggression--> H/W criteria used (antisocial behav.) misleading .. not all anti-social behav. aggressive (e.g. swearing) & not all aggressive behaviour anti-social (e.g. police. army) --> Generalisabilty should be cautioned .. females less testosterone which linked to aggression

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genetic factors III

No gene linked to violent crime (e.g murder, mugging) but likely inherited temperament & personality characterisitics make someone more susceptible to commiting violent crime--> Adoption studies highest rates of criminal violence occur both bio. & adoptive parents history of violent crime --> H/W BRENNAN: gentic influences signif. in terms of property crime (e.g. burglary, vandalism) not violent crime

Issues w/METHODOLOGY in the area of research: most studies focus individ. convicted violent crime = 2 PROBLEMS: (1) convictions for violent crime very few compared to number violent attacks that don't result in conviction therefore repres. small minority of those involvd in aggress. behaviour ... (2) crimes described violent in court not necessarily most serious/habitual as ciminal sent straight to psychiatric ward & not all cases fully described in court b/c soo horrific --> Expalins why studies found little evidence of hereditability of violence

MILES: meta-analysis of 24 twin & adoption studies & results suggests 50% link b/twn genes and aggres. --> Genes & environmental factors very strong in influencing aggress. in youth--> H/W later on environmental decreases & genes become more powerful --> RHEE  CONTRADICTS.: meta-analysis 51 twin & adoption studies and concluded aggression product of genetic influences --> H/W limitation of meta-analyses ... level of control in each study not ascertainable

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