Abstract

Aftereffects of adaptation to spatial grating stimuli have been studied intensively in photopic vision over the last 20 years. However, it was shown only recently that such aftereffects also occur when the adapting grating modulates only rods or cones and the test grating modulates only the other receptor type, suggesting the adaptation of some portion of a pathway shared by rod and cone signals.¹ We show here that the site of adaptation displays both orientation and spatial-frequency tuning. We measured photopic luminance-modulation thresholds (not contrast-modulation thresholds) for resolving square-wave and sine-wave gratings after adaptation to scotopically detected gratings at 7° eccentricity. Test gratings were 670 nm and 200-ms duration. Adapting gratings were 490 nm, 0.67-Hz counterphase flickered, and presented for 120 s before the first test stimulus and for 3 s before subsequent test stimuli. The interaction aftereffect was found to have an orientation tuning half-bandwidth at half-maximum of 15-20° and a spatial-frequency tuning half-bandwidth at half-maximum of less than an octave.

© 1986 Optical Society of America