What Is Causing the Flynn Effect?
To the best of my knowledge, the causes of the Flynn Effect are still uncertain. Several plausible explanations have been advanced, such as improved nutrition, increasing test-taking sophistication, the improved education and the influence of movies, TV and more recently, computer games upon developing minds. It has been shown that each of these could have had some influence upon IQ's, but none of them is adjudged sufficient to explain more than a fraction of the effects that are observed. Well-funded attempts to boost IQ's through early mental stimulation have been disappointing. One of the conundrums concerns the steady 3-point-per-decade improvement in IQ test scores decade after decade*. Nutrition is an example of an imperfect fit. In the U. S., heights began to level off in the 70's, suggesting that nutrition had become adequate for most U. S. children, and yet, IQ's have continued to increase at the same 0.3%-per-year rate.
* - There have been some fluctuations in the rate over the years, but to the best of my knowledge, there has been no slowing of the pace..