Accession Number : AD0663646

Title :   THE EFFECT OF ILLUMINATION LEVEL AND OF FLASH BRIGHTNESS ON BLOCKING THE ALPHA RHYTHM OF THE EEG WITH LIGHT.

Descriptive Note : Memorandum rept.,

Corporate Author : NAVAL SUBMARINE BASE NEW LONDON CONN

Personal Author(s) : Harris,J. Donald

Report Date : 17 SEP 1952

Pagination or Media Count : 11

Abstract : Four subjects with normal alpha rhythm in the encephalogram were dark adapted to one of two levels, and presented with a light flash at one of two intensities. In all four subjects the brighter flash blocked the alpha rhythm quicker in the higher level of dark adaptation than the same flash in the lower level of adaptation. This is the opposite from the effect of adaptation level on motor reaction time to a constant-intensity light flash, and is similar to the effect of adaptation level upon speed of appearance of the electro-retinogram. At the same level of dark adaptation, the brighter flash produced longer latencies than the weaker flash. These results may be allied to the view of alpha as concerned with pattern vision; in the dark adaptation situation here, the brighter flash allowed no figure-ground structuring to appear for an appreciable time. (Author)

Descriptors :   (*VISION, ADAPTATION(PHYSIOLOGY)), (*ELECTROENCEPHALOGRAPHY, VISUAL SIGNALS), BRIGHTNESS, ILLUMINATION, RESPONSE(BIOLOGY), ELECTROPHYSIOLOGY

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE