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The importance of environment on cognitive ability

11 May

Adoption is the closest thing we have to licensed parenting, in most jurisdictions a potential parent is screened by some agency before being allowed to adopt. In situations where one child is adopted and a sibling remains with the biological parent we have the conditions for a natural experiment – a test of the importance of effects of nurture on cognitive ability.

A study published this year analyses 436 such cases. From the paper:

“Individual differences in cognitive ability result from a complex admixture of genetic and environmental influences. Adopted children are one way to estimate the degree of malleability of cognitive ability in response to environmental change in the context of a scientific design that can control for genetic differences among individuals. Sibling pairs in which one member is adopted away and the other reared by biological parents are a particularly powerful research design. In a large population-based sample of separated siblings from Sweden, we demonstrate that adoption into improved socioeconomic circumstances is associated with a significant advantage in IQ at age 18. We replicate the finding in a parallel sample of half-siblings.”


Superior autobiographical memory

1 Feb

An article (unfortunately behind a pay wall)  in the most recent Scientific American examines people with superior autobiographical memory. The article points to evidence that this superior ability to recall life events has a biological basis. This is more evidence that there are real individual differences in memory.

Here is a video about superior autobiographical memory:

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Not genes versus environment

20 Dec

Most people think that the question is nature versus nurture. The reality is much much complex and much more interesting.

The current issue of The Observer, a publication of the Association for Psychological Science, includes the following quiz:

  1. Cognitive ability in the industrialized world “is approximately 50% to 70% heritable,” reports the Tucker-Drob team. This means that
    1. 50% to 70% of one’s cognitive ability is attributable to one’s genes.
    2. 50% to 70% of the variation among individuals is attributable to their genes.
  2. The genetic influence on intelligence scores (heritability) is greatest
    1. early in life (for example, at age 3), before varied experiences diverge our life courses.
    2. later in life (for example, at age 50 and beyond).
  3. The genetic influence on intelligence scores is greatest among those
    1. at lower socioeconomic levels.
    2. at higher socioeconomic levels.
  4. Increasing the quality and availability of educational opportunity serves to
    1. decrease the genetic influence on intelligence scores.
    2. Increase the genetic influence on intelligence scores.

You can find the answers here. For a deeper discussion see the original paper.

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