kensler 2015, Caspi 2003, and Scarr and weinberg Flashcards
When was Kendler?
2015
What was the aim of Kendler?
to understand the impact of genetics and environmental factors on cognitive abilities, focusing specifically on IQ.
What was the procedure
They took over 400 sibling pairs from Sweden. Including both adoptive and biological siblings. They tested all participants IQ’s, and the scores were compared to the participants biological and adoptive parents.
What were the results of Kendler
Adopted children had a strong IQ connection with their biological parents. Supporting the genetic influence in intelligence. There was a slightly weaker but still significant correlation between adopted children and there adopted parents. Showing the adopted environment also had an impact on cognitive development
What does Kendler show about genes in behaviour
The results highlighted the relationship between genes and the environment in behaviour. Genes provide a strong baseline for potential intelligence, then the environment influenced the expression of intellegence especially as children adopted into higher socioeconomic famalies were shown to have higher IQ’s.
Strengths of Kendler
The study had a large representative sample, so it has high reliability.
Limitations of Kendler
There was some selective placement bias because adopted children are often placed in favorable environments, inflating the environmental influence.
Results cannot be generalized to outside Sweden due to cultural and social differences.
what year was Scarr and Weinburg
1983
what was the aim of scarr and Weinburg
to investigate the influence of environment on intelligence by examining IQ development in African American children adopted by white families.
What was the procedure for scarr and weinburg
They took 101 families that had both biological and adopted children. The adopted children were African American adopted into white middle/upper-class families. They did IQ tests on the adoptive children, siblings and parents as well as the biological parents.The IQs of the adopted children were compared to the adopted parents and siblings, and the biological parents.
What were the results of Scarr and weinburg
·Adopted disadvantaged children had higher IQs than African American children raised in their biological families. Suggesting environmental influences. But their IQs were still lower than those of biological children in the adoptive families, indicating genetic influence.
What does scarr and weinburg show about genetics and enviroment
It found that children’s IQs were moderately correlated with their biological parents, indicating a genetic influence, but also strongly correlated with their adoptive parents, showing the impact of an enriched environment. Additionally, children from disadvantaged backgrounds often had higher IQs when raised in middle-class adoptive families, demonstrating how the environment can enhance genetic potential. This highlights that intelligence results from both genetic inheritance and environmental factors working together.
Strengths of Scarr and weinburg
Provides clear evidence of environmental effects on intelligence.
addresses social and racial issues related to education and adoption.
Limitations of scarr and weinburg
This study also had Selective placement bias, because adoptive families are typically of high socioeconomic class. It may oversimplify the interaction between genetic predispositions and enriched environments. Long-term follow-up is needed to assess whether the IQ gains persist into adulthood.
What year was Capsi?
2003
what is the aim of Caspi
to investigate the role of the 5-HTT gene (a gene involved in serotonin transport) and stressful life events in the development of depression.
Procedure of Caspi
They gathered over 800 people in New Zealand who were 26 years old. They anylayzed participants DNA to find their 5-HTT gene varient. Participants completed self-reports of stressful life events that occurred between ages 21-26. They did a depression report to measure there symptoms and the severity. They also recorded weather they had MDD.
Results of Caspi
Participants with one or two short alleles in the 5-htt gene self-reported to respond with depression in a stressful event. The group with two long alleles were less likely to develop and self reported less depressive reactions.
What did caspi show
Specific molecular mutations can lead to particular behaviors, like how the short allele led to depression. It highlighted how genetic vulnerability can accentuate environmental effects on behavior. But those with two long alleles were more resilient to stress, showing that genetic factors can also provide protection, response against environmental factors.
weakness of caspi
The study is correlational between the 5hhtd gene and reaction to stress
It doesn’t show that if you have that allele you will suffer depression its a response to life events.
The study relies on the extent to which low serotonin is purely responsible for depression only if that is the case can this study be excepted.
It was self reported so the actual life event may have been the reason for depression not the allele.
People who are more resilient may not have seen other people put as stressful as stressful events or not even have reported it because they pushed through it better than others
Strengths of Caspi
The study does acknowledge the interaction between genes and environment which is a good holistic approach.
This study has been replicated with similar results which means it has high reliability
