Agg- Genetic factors- MAOA gene (neural&hormonal mechanisms in agg) Flashcards
what is the 2nd theory in the biological explanations of aggression
1st was neural and hormonal
2nsd is the genetic factors e.g. twin studies
What is the name of the researcher who studied twin studies
what was the gender of the sample
Coccaro et al 1997
male ppts
What were Coccaro et al 1997 findings
Concordance rate of
50% in MZ (100% share genes)
19% in DZ (50% share genes)
Coccaros research supports the role of genetics in aggression as they mz twins that are 100% were more likely to display criminal Behaviour than Dz twins
what’s a limitation of Coccaro et al
a limitation is that it is hard to separate nature and nurture as they grow up in the SAME environment
What is the supporting evidence for twin studies that is researched by ______ and _____ 2002 using adoption study
Rhee and Waldman 2002 who did a meta analysis of 52 twins and adoption studies
what were the findings of Rhee and Waldman
That environmental factors can only be an explanation for aggression if there’s a genetic predisposition to aggresion present
what is a strength and weakness of Rhee and Waldman 2002
strength - high reliability as it is meta analysis and it is secondary data
weakness- adopted children may have past traumatic experiences
define what an MAOA is
MAOA is an enzyme that breaks down important neurotransmitters in the brain ( serotonin, dopamine)
What is held responsible for the production of the MOAO ENZYME- leads to agg behaviour
A gene
What happens if there is a dysfunction in the operation of this gene
may lead to abnormal activity of the MAOA enzyme which affects levels of serotonin as lower levels lead to aggression
How does the MAOA gene turn into the warrior gene
If theres low activity- then theres less production of an enzyme forming MAOA-L
but high activity forms MAOA-H
how is activity levels of the MAOA gene affect aggression
warrior gene is a variant of MAOA gene and if theres low MAOA activity in the brain
it associated with aggressive behaviour
name the researcher who studied the warrior gene
Brunner et al 1993
what was Brunner’s procedure in studying MAOA gene
study a family who were repeatedly involved in aggressive behaviour
5 generations of a dutch family
procedure:
- 8 males - measured MAOA enzyme and did genetic screening
-took a personality test - and physical test
-interviewed for behavioural traits and history
what was Brunner’s findings in studying MAOA gene
Found that they had abnormally low levels of the enzyme
- All had MAOA-L
-low IQ
what is a weakness of Brunner’s study
Brunner et al.’s (1993) research has been criticised for using a case study method therefore lack representativeness. This matters because it is difficult to apply the results beyond the family in question, since the genetic make-up is unique to them.
- A correlation doesn’t mean causation
- reduces population validity
- finding out their IQ doesn’t relate to aggression
what were the strengths of Brunner’s study on MAOA in a family study
- different types of data collected, increases the validity of the research
- it is research support
what is the other section of genetic factors, which isn’t MAOA gene
The Gene-Environment (GxE) interactions
which is the diathesis stress model
what is the researcher who studied the (GxE)
Frazzetto 2007
What approach did Frazzetto take to explain agg behaviour
An interactionalist approach
what did Frazzetto find
found that low MAOA levels only lead to aggression when accompanied with traumatic childhood events in the first 15 years of their life
this is because the genetic mutation of the MAOA gene associated with the environmental stressor of childhood trauma lead to aggression
Evaluating genetic factors of agg- a strength and weakness
strength of genetic factors is research is objective- use of meta-analysis (Rhee and Waldman), brain scanning
leads to more reliable supporting evidence for influences of genetic factors
Strength- MAOA gene research - offers explanation for uneven rates of violence in males and females
e.g. MAOA gene is linked to X chromosome- so males- more likely affected by it because females already have an X- so less abnormal expression of the gene occurs in F
Evaluating genetic factors of agg what are the two weaknesses of the genetic factors of aggression
weakness- it is reductionist as the genetic side in GxE is overemphasised- frazzetto didn’t consider the environmental side of the interaction- led to crucial factor being missed in the research
Weakness of genetic factors- sampling issues- lacks population validity
e.g. brunner- family case study
e.g. Frazzetto only uses male ppts
