In the Scientific American article that links to my blog, there’s a link to a study correlating chess skill with IQ. The correlation with general intelligence is 0.35 (see table 1), which is not a weak correlation, but not a strong one either.
When I was a kid I thought there should be an almost perfect correlation between chess and IQ, especially after my high school chemistry teacher defined intelligence as the ability to adapt: to take whatever situation you’re in and turn it around to you advantage. For chess is all about adapting to a changing board, and turning it to your advantage; maximizing strengths and minimizing weakness.
So why is the correlation not higher?
1) Practice: Malcom Gladwell popularized the idea that you need 10,000 hours of practice to be truly good at a complex mental task, and while that claim has largely been debunked, it applies more to chess than other fields because there are so many strategies that can be explicitly taught. Also, the tendency to practice chess to the exclusion of all else might be negatively correlated with IQ, since smarter people tend to have a wider range of interests and opportunities.
2) Chess is only one type of environment: A talent for chess might not correlate well with other situations where you must gain an advantage over a rival such as trial law or debate clubs.
3) IQ tests are not perfect measures of intelligence: I think chess measures a part of intelligence that IQ tests miss…and one of the most important parts. The ability to think strategically and the ability to make wise decisions; judgement.