Rapid stream stimulation and the recognition potential.

The "recognition potential" is an electrical response of the brain that occurs for recognizable, but not for non-recognizable, images. When a recognizable image evokes it, the more rostral of a pair of vertically oriented occipital electrodes reaches an initial positive peak at about 200-250 msec. Several properties distinguish this component of the evoked response from event-related potentials such as N2 or P3. A new method of stimulation was devised that evoked the recognition potential for recognizable images, but virtually no response of any kind for non-recognizable images. This was accomplished by presenting images at high rates. Chinese ideographs evoked it for subjects whose native language was Chinese, but not for subjects unfamiliar with that language. This showed that the recognition potential was not caused by differences in the physical attributes of the images per se. Instead, recognizability, as defined by a subject's individual learning experience, was the important factor.