BIOLOGICAL - STUDIES Flashcards
classic study: Raine et al 1997
AO1:
AIM: to find out if brain structure is different between murderers NGRI compared to non-murderers
IV: whether the ppt is a murderer NGRI or a non-murderer
DV: relative glucose levels (shown by PET scans)
SAMPLE: 41 ppts, 39 men and 2 women, mean age 34.3, all NGRI tried in California, ppts matched on mental illness (6 had SZ) and left/right handedness
CONTROL OF EVs: matched pairs design
PROCEDURE:
1) 10 mins before the FDG, subjects were given practice trials of the CPT
2) the FDG tracer was injected into the ppt in a test room an was taken up by the brain for 32 mins
3) during this time, the ppt completed the CPT, which consisted of pressing a button to indicate when they had spotted a target on a screen
4) after the 32 minute period, they were transferred to an adjacent PET scanner (10 slices, 10mm intervals to the cathodic line was obtained - the brain regions were identified using the cortical peel technique, allowing glucose regions to be found in each area)
RESULTS:
->amygdala (left hemisphere): murderers had lower glucose metabolism (0.94) than non-murderers (0.97)
->parietal lobe (left hemisphere): murderers showed lower activity (1.10) than non-murderers (1.15)
CONCLUSION:
->deficits in the PFC might make someone more impulsive, deficits in the brain make it harder for someone to identify the difference between right and wrong
AO3: EVALUATION
G->(weakness) low generalisability as all criminals pleaded NGRI
–>the same findings may not be true of violent offenders who do not plead NGRI
–>therefore, decreasing the generalisability of the findings
R->(strength) high reliability
–>the study was carried out in a controlled lab environment, meaning there was high control of EVs and a standardised procedure was followed: practice CPT, FDG tracer injected, CPT task performed, PET scan
–>therefore the findings can be tested for consistency
A->(strength) research findings can be applied IRL
–>the research findings suggest that reduced brain activity in certain areas may act as a predisposition for violence
–>therefore, violent criminals may be less accountable for their actions, this has importance when sentencing is decided in court
V->(strength) high internal validity
–>matched control group to experimental (NGRI) group in terms of age, sex, mental illness (SZ), and right/left handedness
–>therefore, reducing the effect of ppt variables
E->(weakness) ethics are questionable
–>informed consent was given by murderers NGRI, meaning they likely were not in a fit state to give informed consent or may have felt pressured to take part
–>this means their right to withdraw was compromised
contemporary study: Brendgen 2005 (twin study)
AO1:
AIM: to see if social and physical aggression could be caused by genes or the environment, and to see if one type of aggression leads to another
IV: MZ or DZ twins
DZ: score for aggression on teacher/peer ratings
SAMPLE: 234 twin pairs recruited through the QNTS
PROCEDURE:
1) data from the sample was gathered longitudinally at 5, 18, 30, 48, and 60 months; and then again at 6 years - it is the final data that researchers focused on
2) the data consisted of 2 ratings of each of the twins behaviour - 1 by their teacher and 1 by their peers
3) teacher ratings were based on an agreement with a series of statements taken from the “Preschool Social Behaviour Scale” and the “Direct and Indirect Aggression Scales” such as “to what extent does the child try to make others dislike a child?” (social aggression) and “to what extent does the child get into fights?” (physical aggression). The scores were given on a 3-point scale
4) peer ratings were given by other children in the twins classes, they were asked to circle 3 pictures of children (out of the children in their class) who they thought matched with 4 different behaviour descriptions (eg. “tells others to not play with a child” - social aggression, and “gets into fights” - physical aggression)
RESULTS:
->scores for social aggression were roughly equal between MZ and DZ twin pairs
->much higher correlations between MZ twins than same sex DZ twins on physical aggression
->physical aggression may lead to social aggression but not the other way around
CONCLUSION:
->there seems to be a strong correlation between physical aggression, but not social aggression, which is more likely to be due to environmental affects
AO3: EVALUATION
G->(weakness) low generalisability
–>the age group studied is very specific (up to age 6) and the sample is ethnocentric as they were all recruited through the QNTS
–>therefore results may not be representative of aggression in older children or teenagers, or people from other countries
R->(strength) high reliability due to SP
–>data was gathered at 5, 18, 30, 48, and 60 months, then again at 6 years old. Data consisted of teacher ratings (3 point scale from “Direct & Indirect Aggression Scale” and the “Preschool Behaviour School”) and peer ratings from assigning students to 4 different behaviour descriptions
–>therefore can be tested for consistency
A->(strength) findings can be applied IRL
–>it was found that social aggression is likely to be caused by environmental factors, meaning parents can try to prevent social aggression in their child by encouraging them to be kind
V->(strength) high internal validity:
–>measures of the twins aggressive behaviour came from 2 different sources: teacher and peer ratings
–>therefore, highlighting or eliminating bias. The teachers were in agreement with each other, further increasing validity
E->(strength) highly ethical
–>the experimenters had fully informed consent from the parents of all the children who were involved
–>therefore no ethical guidelines were broken, can be replicated
named study: Heston 1966 (adoption study)
AO1:
AIM: to see how many adopted children of biological mothers with SZ would develop SZ
IV:
DV:
SAMPLE: experimental group - 47 adoptees born to mothers with SZ confined to an Oregon State psychiatric hospital, adopted at birth // control group - 50 adoptees born to mentally healthy mothers
CONTROL OF EVs: the subjects were matched for age, sex, type of eventual placement (adoptive/foster/institutionalised), and the length of their time in care
PROCEDURE:
1) the ppts were contacted by letter and asked to participate in a personal interview
2) the purpose of the interview was to see whether any of them had gone onto develop SZ themselves. Nearly all interviews were carried out in the ppts own homes
3) the short form of the Minnesota Multiple Personality Inventory (MMPI) was given after the interview
4) the info compiled on each ppt was evaluated blindly and independently by 2 psychiatrists, a final evaluation was then made by a 3rd researcher. (2 evaluative measures were used: a numerical score 100-0 was assigned for each ppt based on the landmarks of the Mental Health-Sickness Rating Scale (MHSRS)
RESULTS:
->5/47 had been hospitalised with SZ
->none of the control group had developed SZ, indicating the experience of adoption was not a contributing factor
CONCLUSION:
->the study provided powerful evidence for the role of genetics (not environment) in SZ
AO3: EVALUATION
G->(weakness) low generalisability
–>a volunteer sample was used to recruit the adopted individuals
–>this limits the generalisability as the volunteers may have shared characteristics and therefore may not represent the whole target population
R->(strength) highly reliable
–>the interviews that were use to ascertain the mental health of the adopted individuals had standardised questions
–>this means the questioning of the ppts was consistent and the procedure itself was easily replicable
A->(strength) application IRL: genetic modification
–>as the results have shown, SZ is a genetic condition. This means that if the mother has SZ there is a 10% chance the baby will too. This may lead to the termination of the pregnancy
V->(strength) high internal validity due to high control of EVs
–>matched pairs design was used: ppts matched on age, sex, event placement (foster/adoptive/institutionalised), and length of time in care
–>therefore reducing anomalies in the data so we can establish the cause and effect that SZ is inherited
E->questionable ethics
–>the nature of the research (whether they have developed SZ and whether this links to their birth mother, who also has the condition) is highly sensitive
–>therefore, the testing and interviewing of the ppts may have been distressing in light of the aims of the research
