The victories of China at the recent Team World Championship and of Lei Tingjie at the Women Grand Swiss 2021 cannot be estimated highly enough. The Chinese players voluntarily played with masks even though many felt that this impedes performance which was also suggested by the low number of publishable games in events were mask use was mandatory. A new study has confirmed this long-held suspicion.
David Smerdon, a grandmaster and economist at the University of Queensland in Australia, collated almost 3 million moves made by 8,531 players, partly from tournaments with mandatory mask use, partly by the same players in earlier editions of the same tournaments before the pandemic, and had them analysed by Stockfish. Playing with a mask decreased the share of moves which matched the best move according to the computer.
A 2500+ player in a high-incentive game will play the middle game at least 100 Elo weaker.“
While the effect was little or insignificant for weaker amateurs, it was biggest among players above 2500 in competitions with higher stakes. Asked for an estimate, Smerdon told ChessTech, ”for a 2500+ player in a high-incentive game, a ballpark estimate is that they will play the middle game 100+ Elo weaker.“ His explanation is that Grandmasters rely more on their working memory, which tends to be impeded by getting less oxygene and the nuisance of having to wear a mask.
The effect is much more pronounced during the first half of a game, while there is little or no relative quality loss in the second half of a game. This suggests that players are getting used to wearing a mask but may also have to do with masked players approaching the game less ambitiously to save energy. Smerdon observed a bigger loss of quality in high stake competitions than in other events. While he excluded the games of juniors from the larger sample because their ratings are much less reliable indicators during the pandemic, a separate analysis suggests that the juniors’ game didn’t suffer from wearing masks. His data didn’t confirm a stronger effect on older adults compared to younger adults but suggest a bigger effect of masks on women, but this isn’t entirely clear because most of women games in the sample were from high stake events. The PNAS original article is behind a pay wall until June, but a nearly identical draft version is publicly available.
The study has not only implications for chess organisations, which tended to mitigate Covid risks by all kinds of equipment rather than make competitions safer in the open air, but also for other contexts where cognitive tasks are performed by specialists or for academic examinations. Thanks to its richness in rating and game data chess is often used as a natural experiment. Recent studies established the effect of indoor air quality or particles in the air on cognitive work or moving it from its usual space to the home office.