Addendum: Stimulants mess with your sense of time. Time management is an important part of playing chess, but surely players don’t do it by looking at the clock, but by heuristics about how much to think, heuristics that could be messed up by their sense of time. So I think that the time management would be improved by practice with the drugs. Most chess players probably have practice at varying levels of caffeine, so the study is a more fair comparison of that drug than the others.
Added later: Indeed, caffeine lead to fewer losses on time than modafinil and methylphenidate, although more than placebo, even though raw win/loss/draw numbers were the same for the three drugs. (Oddly, although the score excluding games lost on time puts modafinil and methylphenidate together, a more general metric of performance controlling for time groups together methylphenidate with caffeine.)
Addendum: Stimulants mess with your sense of time. Time management is an important part of playing chess, but surely players don’t do it by looking at the clock, but by heuristics about how much to think, heuristics that could be messed up by their sense of time. So I think that the time management would be improved by practice with the drugs. Most chess players probably have practice at varying levels of caffeine, so the study is a more fair comparison of that drug than the others.
Added later: Indeed, caffeine lead to fewer losses on time than modafinil and methylphenidate, although more than placebo, even though raw win/loss/draw numbers were the same for the three drugs. (Oddly, although the score excluding games lost on time puts modafinil and methylphenidate together, a more general metric of performance controlling for time groups together methylphenidate with caffeine.)