We present data and argument to show that in Tetris—a real-time, interactive video game-
certain cognitive and perceptual problems are more quicklv, easily, and reliably solved by
performing actions in the world than by performing computational actions in the head alone.
We have found that some of the translations and rotations made by players of this video
game are best understood as actions that use the world to improve cognition. These actions
are not used to implement a plan, or to implement a reaction; they are used to change the …