Biological Psychology - Studies Flashcards
What was the aim of Raine et al’s study?
To investigate whether ppts pleading NGRI (not guilty by reason of insanity) would show brain dysfunctions in areas of the brain associated with violence.
What was the procedure of Raine’s study?
Sample - 39 men and 2 women for each group.
The participants were tested at the University of California.
Each was injected with the glucose tracer and then performed the Continuous Performance Task (CPT) for 32 minutes. The PET scan was then carried out.
Raine used other experimental controls - ppts practiced the CPT ten minutes before glucose tracer injection.
NGRIs and control group kept medication-free for 2 weeks before PET scan.
What was the results of Raine’s study?
Murderers had lower glucose metabolism/less activity in areas previously linked to violence i.e lateral + prefrontal areas, corpus callosum, left amygdala and hippocampus.
Murderers showed greater activity in the right amygdala, right medial temporal lobe, right thalmus and occiptal lobe - brain areas not previously linked to violence or implicated in violent behaviour.
What was the conclusion of Raine’s study?
There are differences in the brain activity of murderers and non murderers, but dysfunctions of a single brain area cannot explain violent behaviour completely.
The differences were particularly in the pre-frontal cortex, parietal cortex, amygdala and thalamus. Prefrontal deficits can increase impulsivity and emotional instability.
Generalisability of Raine’s study?
Large sample size of 82 - due to the large size any anomalies wouldn’t disrupt the data
However NGRI murderers are not common - therefore not representative.
Reliability of Raine’s study?
PET scans are a reliable brain imaging technique
The CPT also ensured that all the participants were focused on the same thing which means they would have similar brain activities
However, Raine admitted that some of the results were unclear/subjective, which lowered reliability.
Application of Raine’s study?
Raine suggested that If the damage that can cause these brain deficits can be prevented it may prevent people from becoming murderers
It can also be used for early intervention for at-risk children.
Validity of Raine’s study?
17 studies, including Raine’s, all used brain imaging to study aggression and all pointed to the same conclusion.
This adds to construct validity as it ties into the results of other similar studies.
Lacks ecological validity due to artificial environment.
No clear cause and effect as NGRI’s may have developed a brain deficit after murder - reductionist to say aggression is all biological.
Ethics of Raine’s study?
NGRI’s agreed to a PET scan as it would support their case
consent was given.
Ethical concerns over the conclusions as it could lead to screening for a “murderers brain” and this goes against social responsibility.
What was the aim of Brendgen et al’s study (2005)?
To find out if there is a difference between physical and social aggression in 6-year-old school children by surveying their teachers and classmates.
What was the sample of Brendgen’s study?
Twins were assigned to MZ or DZ based on physical resemblance, with 123 pairs DNA-tested. By age 6, 88 pairs had dropped out of the study.
Brendgen obtained data on the remaining 234 pairs, obtained written consent from parents, and approached their schools.
What was the procedure of Brendgen’s study?
Teachers’ questionnaires asked them to rate each child on a 3-point scale on six statements: tries to make others dislike a child, says bad things or spreads nasty rumors about another child, becomes friends with another child for revenge, gets into fights, physically attacks others, and hits, bites or kicks others.
Childrenalso rated their peers by circling photos of three children who fit four descriptions: telling others not to play with a child, telling mean secrets, getting into fights, or hitting, biting, or kicking others.
The scores for social aggression and physical aggression were added together to produce two overall scores.
What was the results of Brendgen’s study?
Only 20-23% of social aggression explained by genetics.
Physical aggression mostly explained by genetic factors.
Social aggression mostly explained by non-shared environmental factors.
Moderate but significant correlation between physical and social aggression.
Statistical testing showed high physical aggression = social aggression but the opposite not true
What was the conclusion of Brendgen’s study?
50-60% of physical aggression can be linked to genes, since it was shared by MZ twins but not so much by DZ twins.
For social aggression, genes only seem to account for about 20%.
A “non-shared environment” was considered as an influence, which would be outside influences other than home life. This seems to account for the other 40% of physical aggression and 60% of social aggression.
Generalisability of Brendgen’s study?
Large sample; 234 twin pairs - representative
However, 88 twin pairs left before the age of 6 - sample attrition - could have affected the study.
Only 6 year olds used - not representative.
