A Review of Adoption and Cognitive Development: A Meta-Analytic Comparison of Adopted and Non-adopted Children’s IQ and School Performance

A Review of Adoption and Cognitive Development: A Meta-Analytic Comparison of Adopted and Non-adopted Children’s IQ and School Performance.

A meta-analysis of multiple studies was done by van Ijzendoorn, Juffer and Klein Poelhuis (2005) to determine if cognitive development in children is affected by adoption. Cognitive development is “the emergence of the ability to understand the world” (Schacter, Gilbert and Wegner, 2008, p. 412). There have been studies done that show behavioural problems occurring as a result of adoption and van Ijzendoorn et al. wanted to see if cognitive development was also affected. Van Ijzendoorn et al. looked at studies comparing cognitive development of adopted children to children who stayed where the adopted children came from. They also compared cognitive development of adopted children to their non-biological siblings and peers in their new environment (van Ijzendoorn et al.). Cognitive development was measured by IQ and school performance (van Ijzendoorn et al.).

In the comparison of adopted children to children who stayed behind, the adopted children went from an environment change from bad to good whereas the children who stayed would be just exposed to a bad environment. A reasonable prediction is the adopted children’s cognitive development would be effected less than the children who stayed because the adopted children have a change to a good environment. In the comparison of adopted children to their non-biological siblings and new peers, the non-biological siblings and new peers would be just exposed to a good environment. A reasonable prediction is the adopted children’s cognitive development would be more effected because they started in a bad environment and have been moved around. A bad environment could be the birth family’s home or an orphanage. These could consist of malnourishment, neglect, abuse, lack of interaction with people or toys and lack of ability to explore the world for themselves (van Ijzendoorn et al., 2005).

Van Ijzendoorn et al. (2005) found that tests comparing adopted children and their siblings or peers who stayed behind showed the IQ and school performance of the adopted children was better than the siblings or peers who stayed behind. When van Ijzendoorn et al. looked at tests comparing adopted children and their new environmental siblings or peers they found there was no difference in IQ. However the adopted children’s school performance was significantly less than their new environmental siblings or peers, they appeared to have more learning problems requiring treatment and they have some delay in language development (van Ijzendoorn et al.). They also found that the age when adoption occurred affected if there was a drop in school performance, only adoption after a year old affected school performance (van Ijzendoorn et al.).

From these results it would seem there is a positive effect on cognitive development of adopted children when being moved from a bad environment to a good environment (van Ijzendoorn et al., 2005). However there was limiting data comparing the cognitive development of adopted children to the ones left behind and the cognitive development of children could be causing which ones are picked for adoption, affecting results (van Ijzendoorn et al.). Also there is no data on the cognitive development of the children before adoption so it is hard to tell if there is really a change (van Ijzendoorn et al.). In tests looking at correlation between IQ scores of non-biological siblings living in the same house, there was a significant correlation suggesting the environment a child is in has an effect on cognitive development (Schacter et al., 2008). This means the switch to a good environment would play some role in the cognitive development of the adopted children. Taking everything into consideration it can be said there needs to be more data analysed and more factors considered before a definite conclusion can be made.

References

Schacter, D. L., Gilbert, D. T., & Wegner, D. M. (2008). Psychology 104/105. New York NY: Worth Publishers.

van Ijzendoorn, M. H., Juffer, F., & Klein Poelhuis, C. W. (2005). Adoption and cognitive development: A meta-analytic comparison of adopted and non-adopted children’s IQ and school performance. Psychological Bulletin,131(2), 301-316. doi: 10.1037/0033-2909.131.2.301