Practicing a perceptual skill dramatically alters the way the visual system works, according to a study that appears in the Dec. 24, 2002 Proceedings of the National Academy of Sciences. For people tested on their ability to spot subtle visual distinctions, practice on the task beforehand results in intensified activity in the neural gateway for information from the eyes, say Sophie Schwartz of University College London and her colleagues.
In a single session, Schwartz's group trained 16 adults to make visual discriminations using only one eye. Volunteers had to identify a central letter–either L or T, each rotated into various positions–as well as the orientation of three solid, parallel lines embedded within an array of dashed lines.
Each display, flashed briefly on a computer screen, appeared in the upper left part of the visual field and, thus, was always projected to the same small region of the primary visual cortex.
The next day, volunt