Abstract
While chess is often seen as a domain requiring a high level of intelligence, the available empirical evidence is far from being clear cut. The results can be summarised as: (a) chessplayers have a higher general intelligence than the general population; (b) within the chess population, there is no correlation between general intelligence and skill level; and (c) surprisingly, there is little evidence that chessplayers have better visuo-spatial abilities than the general population. We present additional evidence from our laboratory: about laterality (chessplayers are more often left-handed than could be expected by chance), seasonal effect (chessplayers with an international rating were born more often in the first half of the year than expected by chance), and visual memory (chessplayers do not perform better than non-players). These results are discussed in the light of research into expert behaviour, which emphasises acquired knowledge, and of research into talent, which emphasises innate abilities. In the conclusion, we consider the difficulties of drawing causal links from these results.