noun. The visual which stays present even after a stimulant ceases or is taken away. A positive doesn't happen very often and only remains for a couple moments. It occurs due to the ongoing receptor and neurologic activities that are subsequent to the ceasing of the stimulant. It's appearance in terms of color and contrast are quite similar to the stimulant of origin. More frequently, a negative takes place, commonly in more insensitive manner, and usually continues for a longer period of time too. It is typically a well-suited companion to the stimulant of origin with regard to color and contrast.