Do puzzles: There is a correlation between doing puzzles and increased scores on mental tests. (thoughtfullaw.com)
So why would it be a «huge mental test» unless he was set to play against the team he should have been playing in? (justarsenal.com)
Before and after the supplementation, the researchers subjected the students to a whole battery of mental tests that you would expect to cause mental stress. (ergo-log.com)