A test of seasonal effects on cognition in tournament chess players

<p>Research has revealed considerable seasonal variation in human behaviour and emotion. However, whether cognitive performance is similarly seasonal remains an open question. While some studies have found a performance advantage in summer compared to winter, others have found either the reverse effect or no effect at all. Because demographics, locations, and cognitive domains of interest vary between studies, it is difficult to determine whether such heterogeneity reflects systematic variation due to study characteristics or whether significant findings are better explained by sampling variance and publication bias. In the present study, we tested for seasonality in 100,113 chess games played by 27,335 players. Not only did we not find a seasonal effect, but we also found no interactions with age, gender, the absolute latitude of the tournament location, and the human development index of a player’s country. Our results suggest that the cognitive capacities required by chess do not vary seasonally, and that there are unlikely to be populations or locations in which it does.</p>