The effect of stroboscopic photostimulation upon an institutionalized, mentally retarded, photoepileptic male was studied. Evidence of epileptiform activity was carefully monitored on a 16-channel electroencephalograph as a stroboscope was systematically moved closer to the subject's face. No sensitivity to photostimulation was noted at 105 cm., whereas, extreme epileptiform activity was evidenced at 10 cm. Results indicate that as the distance between the source of stimulation and the subject decreased, “spiking” on the electroencephalogram (EEG) and epileptiform EEG activity increased.
