IQ gains in rural Kenya

Here’s some good news I didn’t see in the newspapers (and a Google News search for “Kenya IQ” comes back null): what seems to have been a very careful set of measurements shows that the average IQ of children entering school in rural Kenya improved by about a standard deviation and a third (20 IQ points) between 1984 and 1998 on the Raven’s Progressive Matrices, a nonverbal test of symbol manipulation, and by a smaller but still impressive amount on a pictorial vocabulary test (point to the picture showing the object named by the tester). That’s consistent with, though even faster than, a broader pattern called the “Flynn effect”: measured intelligence in the industrialized world has been growing by something like a standard deviation a generation.

This sounds like truly astonishingly good news. If conditions in Kenya today are that much more conducive to cognitive development among children than was true fifteen years ago, then the discouraging statistics on GDP per capita in Kenya and other parts of the what has been called the Fourth World, or group of Non-Developing Countries, may be misstating the reality on the ground. (The life expectancy tables seem to tell the same story.) Moreover, it seems at least plausible that growing cognitive ability should be a direct contributor to measured economic growth through improved productivity and increased innovation.

Some questions:

1. If Daley and her colleagues are right to think that they can measure changes over time in cognitive development among rural children in very poor countries, shouldn’t such measurements be made routinely and incorporated into the set of measures about how well the governments of those countries, and the international agencies that are supposed to be helping them, are doing?

2. The article takes a stab at isolating the factors driving the changes, singling out parental literacy, shrinking family size, and improved nutrition and health. Nailing the key factors down, and learning how to manipulate them, seems like a research task that the World Bank, for example, ought to want to get done.

3. Has anyone tried to integrate population-wide changes in cognitive skill been into models of economic development? If so, what’s a third of a deviation in IQ worth in terms of GDP growth rates?

4. If IQ tests measure something real, which they certainly seem to, and if scores on those tests have been rising fairly rapidly for a long time, which also seems to be the case, then in some sense today’s populations should be a great deal smarter than was the case half a century or a century ago. What effects would we expect from such changes? Have they been showing up? My immediate reaction is that they haven’t; at least, it doesn’t seem that today’s popular culture or political discourse shows a huge improvement in cognitive complexity over that of the past. What am I missing here?

Update and correction

Kevin Drum points out that I read the paper wrong (or followed Science News in doing so): the gain was about two-thirds of a standard deviation (11 points) in 14 years, which works out to something over 20 points per thirty-year generation.

Kevin found another paper, this one on Ghana. As far as I can decode, Daley et. al’s Kenyans did much better than a somewhat older sample of Ghanaians; if we adjust for age differences, the Kenyans are within striking distance of an English sample.

Author: Mark Kleiman

Professor of Public Policy at the NYU Marron Institute for Urban Management and editor of the Journal of Drug Policy Analysis. Teaches about the methods of policy analysis about drug abuse control and crime control policy, working out the implications of two principles: that swift and certain sanctions don't have to be severe to be effective, and that well-designed threats usually don't have to be carried out. Books: Drugs and Drug Policy: What Everyone Needs to Know (with Jonathan Caulkins and Angela Hawken) When Brute Force Fails: How to Have Less Crime and Less Punishment (Princeton, 2009; named one of the "books of the year" by The Economist Against Excess: Drug Policy for Results (Basic, 1993) Marijuana: Costs of Abuse, Costs of Control (Greenwood, 1989) UCLA Homepage Curriculum Vitae Contact: