The effect of extent on the intensity-time relation for the visual discrimination of movement.

Abstract

Using 3 human Ss, the relation between speed and luminance of a small visual stimulus in discrimination of movement was tested. Above a given speed movement could not be discriminated and threshold luminance increased in direct proportion to stimulus speed; below the upper speed threshold "threshold luminance for motion discrimination was constant up to a critical rate, beyond which it increased directly with stimulus speed." Extent of movement increased the absolute energy required for discrimination with exposures below the critical duration. 16 references.