Abstract

Subjects viewed a 2.3 × 2.3 O-patch of a moving 1.3 c/d, 3.75 Hz sinusoidal grating, centered at 1.8° temporal, through an achromatizing lens and an artificial pupil. The grating could be modulated in luminance and/or chromaticity, along many axes (azimuths and elevations), through a central white point. Near isoluminance, subjects perceived a clear "dead zone" within which no motion was seen. The upper and lower boundaries of the "dead zone" were perceptually striking and could be rapidly and consistently estimated by the method of adjustment. For the first subject tested, over the entire color gamut of the video system used, the measurements defined two parallel planes separated by twice the luminance contrast threshold. The plane bisecting the motion "dead zone" lay close to the plane defined by Judd's modified Vλ. These results suggest that the motion "dead zone" defines null values for an additive, univariant luminance mechanism and help to legitimize motion photometry as a luminance calibration technique for use with video displays.

© 1990 Optical Society of America