Exam questions Essays
EVALUATE 1 ADOPTION STUDY (8)
One strength of Heston (1966) is that it is reliable. The aim was to determine
whether nature or nurture was responsible for the development of schizophrenia (SZ) by
using an adoption study to separate out these factors. 47 adoptees born to mothers
diagnosed with schizophrenia were matched with other 50 controls that were adopted
but were not born to mothers diagnosed with SZ on gender, type of eventual placement
and length of time in childcare. Different sources were collected for each individual
such as school records, psychiatric hospital records and interviews. This enabled 2
psychiatrists to collect detailed qualitative data which was used to make a diagnosis of
SZ and assess the participants’ psycho-social disability. This increases the validity of
the findings as the reports represent the true behaviour of the participant, which must
be consistent with schizophrenia, so as to draw conclusions between the adoptees born
to schizophrenic mothers and the control group. This is a strength as it means the
findings are valid as they measure what they intend to measure. However, adoptees
normally go to similar adoptive families, which decreases the validity of conclusions
drawn from this adoption study as the similar environment the participants experienced
may be a further contributing factor to the development of SZ and not being born to a
mother with schizophrenia.
One weakness of Heston (1966) is that it has low generalisability. Participants
born to schizophrenic mothers had a lower score regarding psycho-social disability
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compared to the control group, indicating troublesome psychiatric symptoms. The rate
of SZ for adoptees born to SZ mothers was 10.6% compared to 0% in the control group.
This supports the theory of the influence of genes in the development of SZ. However, a
small sample of 47 participants from Oregon was used. This means that findings
cannot be applied to other populations outside Oregon as the rate of SZ for adoptees
may be different in other cultures. This is a weakness as it means that genes may
influence the development of SZ, but this is only found in the study for people in Oregon
born to SZ mothers. On the other hand, a clear genetic link has been found in SZ. This
can have useful applications in the real world so as to develop research to prevent SZ
from being passed on.
In conclusion, Heston (1966) found that adoptees born to SZ mothers had a
higher concordance rate compared to adoptees not born to SZ mothers. This suggests
that genes are involved in the development of SZ and provides further support for the
nature side of the development of mental disorders. However, since it is virtually
impossible to separate completely nature from nurture, it is difficult to assume any
similarities in SZ symptoms between adoptees and the biological family as a result of
nature as they could be due to similar experienced life events since adoptees tend to be
placed in families with similar backgrounds to their biological families.
EVALUATE 1 CONTEMPORARY STUDY / TWIN STUDY (8)
One strength of Brendgen et al. (2005) is that it is reliable. The aim of the study
was to determine any differences between physical and social aggression in 6 year old
school children by surveying teachers and peers, and to see if physically aggressive
children were also socially aggressive and whether this link was down to genetics or
social situation. Teacher ratings for social and physical aggression were calculated out
of 6 each from questionnaires where teachers rated each child on a 3-point scale on 6
statements, with 0 being never and 2 being often. The peer ratings were taken from
classmates who were asked to identify the twins from photographs who fitted various
descriptions, such as if the twins didn’t play with them or told mean secrets about them.
The questionnaires used to measure aggression were established and can hence be
easily replicated as they had the same questions worded in the same way. This means
that the teacher ratings may be valid as every teacher had the same set of questions,
therefore they were more likely to give accurate answers. This is a strength as it enables
the study to be replicated and be checked for reliability, which increases the replicability
of the findings. However, the allocation of zygocity was based largely on appearance.
This is because 123 out of 234 twin pairs were DNA tested, backing up the assignment