Intelligence across the life span

Purpose
The aim of this paper is to present a theoretical explanation as to why young people score higher on IQ tests than their parents would have done at the same age.

Background
It is now well established that IQ tests score higher as they get older by about .3 of an IQ point per year for each year since they were standardized. So if the average 20 year old in 1972 was given an IQ test standardized in 2015 they would get a measured IQ of about 87, whereas the average 20 year old today would get a measured IQ of about 100. This is the Flynn effect, for which there are a number of diverse possible explanations but not a definitive one.

Methods
The literature for the Flynn effect and its possible explanations is considered, including two studies by the current author.

Conclusion
It is likely that the Flynn effect is the result of a number of independent factors. Although some of the factors may result in a genuine increase in intellectual ability, the bulk of it is probably due to a specific increased ability to do IQ tests. It is suggested that this is because modern society makes more intellectual demands on us, presenting us with more situations that are similar to IQ test items and so effectively allowing us to practise doing IQ tests.