A brief perceptual disturbance, such as a strange light or unpleasant smell. Can be beneficial, as they can give people advance warning before the onset of a migraine or seizure.

Example: A woman sees flashing colored lights to her left for a few minutes before the onset of a severe epileptic seizure.

    Last reviewed: By John M. Grohol, Psy.D. on 6 Oct 2008