From Nautilus, on the research value of chess: "Chess — which has been dubbed the 'fruit fly' of cognitive psychology — seems a tool that is purpose-built to show the deficits of an aging brain. The psychologist Timothy Salthouse has noted that cognitive tests on speed, reasoning, and memory show age-related declines that are 'fairly large,' 'linear,' and 'clearly apparent before age 50.' And there are clear consequences on the chessboard. In one study, Charness had players of a variety of skills try and assess when a check was threatened in a match. But no matter what the skill, the older a player was, the slower they were to spot the threat of a check."