To perform the study, Oxford researchers showed subjects graphic images of violence: accidents, crushed skulls, bloody entrails and so forth. Then they asked half the group to play Tetris. The Tetris players reported fewer bad memories of the ugly images than did those who did not play the game.
Naturally, the researchers are looking into how this may help people (certainly military vets) deal with post-traumatic stress disorder.
According to Dr. Emily Holmes of Oxford's psychiatric department, the results are because Tetris helps blocks the mind from storing painful memories. The catch? You must play the game immediately after the traumatic experience. (Pack your emergency Gameboy, folks.)
More specifically, according to Holmes, Tetris has such an effect because the game, for which you must have intense concentration, competes for your brain's resources for sensory information, and interferes with the way sensory memories are laid down in the period after trauma. As a result, fewer flashbacks are experienced afterward. [via; via]