Physicists are familiar with how measured quantities can depend on the reference frame in which the measurements are made, but less well known are psychological analogies. Emily Balcetis of Ohio University in Athens and David Dunning of Cornell University in Ithaca have shown that psychological states can alter perceptions of the physical world.

The researchers surveyed students who were asked to walk across a campus wearing embarrassing clothes with fruit and vegetable themes. Students who felt that they had little choice about doing the task mentally shortened their estimates of the distance by 40%. Those who felt they had freely chosen to do the task tended to cover the distance more slowly, by about 10%.