GENETICS AND BEHAVIOUR Flashcards
genes and behaviour
● Some psychologists believe that both genetics and the environment have an
impact on human behaviour.
● A gene is the unit of heredity, a portion of DNA which codes for a specific
function or trait. We inherit 50% of our genes from each parent.
● the way these genes interact with the environment can influence behaviour.
Study 1
Caspi. et al
information
the 5-HTT gene is a transporter gene of serotonin with both short and long variations.
research has linked different variants to differences in serotonin reuptake
Aim
to investigate relationships between stressful life events and depressive behaviour given the variations in the 5-HTT gene and resulting (implied) decreased serotonin levels
Procedure
+ representative sample of new zealand children with either : both long 5-HTT alleles, both short or 1 long and 1 short allele
+it was a longitudinal study
+ they followed up with participants from the age of 3 till 25 every 2 years
+ at ages 21-25 they were given a “ife history calendar” assessing stressful life events
+ At age 25- participants were assessed for past-year depression based on interviews and reports from participants
results
there was no difference in the number of stressful life events experienced by them regardless of alleles
participants who had both short or 1 short allele had more depressive symptoms than those with both long alleles
conclusion
Variations in the 5-HTT serotonin transporter gene are linked with more +ve or -ve reactions to events
presence of the short allele implies decreased activation and therefore more depressive symptoms
evaluation
+high ecological validity
-not generalisable to other communities
-correlational
-no measure of actual serotonin so inconclusive
STUDY 2
Meyer-lindenberg et al
Aim
to observe how the difference in the MAOA gene affects brain activity when exposed to threat
Procedure
+ independent measures design
+ 142 healthy undergraduates from psychology courses were used
+ split in 2 groups –> 1 had high suppressing MAOA gene (MAOA-H) and 2 had low suppressing MAOA gene (MAOA-L) which is linked with aggression
+ participants’ fMRI scans were observed while they viewed angry/fearful faces
+looked at the level of amygdala activity depending on the difference of the MAOA gene
Results
-when exposed to emotional stimuli, activity in the amygdala was significantly higher in the MAOA-L group
the MAOA-L group also had less grey matter in their amygdala
conclusion
-MAOA-L linked with aggression and they are more likely to be aggressive when exposed to threat
evaluation
+ high ecological validity
+high generalisability
+ replicable
- angry faces may cause discomfort
