What is g?
Keynote address by Bill Dickens, Department of Economics, Northeastern University, Boston, USA
Chair: John Rust, Tuesday 21st July, 9.20 - 10.20, Palmeston Lecture Theatre, Fisher Building
Large secular gains in cognitive ability (the Flynn Effect) show that large, environmentally induced changes in measured cognitive ability are possible, but several studies have suggested that secular gains are not gains in general cognitive ability and this has led some to conclude that they are therefore not substantive.
This paper extends the model of a single cognitive ability presented by Dickens and Flynn (2001) to multiple abilities. It shows that such a model can account for all the important facts about general cognitive ability without postulating any common underlying physiological cause for different mental abilities. A general intelligence factor arises in the model because people who are better at any cognitive skill are more likely to end up in environments that cause them to develop all skills. Scores on the resulting general ability factor can be highly heritable even while they are potentially subject to considerable environmental influence. Loadings of subtest scores on the general ability factor can be positively correlated with subtest heritabilities. In the model, discrimination against a social group in access to cognitively demanding environments can produce subtest score differences from other groups that are strongly correlated with both the g loadings and heritabilities of those subtests. Despite this, there is no reason to expect that meaningful secular gains should be correlated with g loadings across subtests.
The slides from this talk are available on the Brookings Insitute website