Abstract

We have measured thresholds for detection and identification of a vertically oriented sinewave grating vignetted by a two-dimensional spatial Gaussian window. The stimulus appeared as a contrast-reversing grating to the left or to the right of fixation on the horizontal meridian and then moved either towards or away from the fovea. The temporal frequencies of the contrast reversing and drifting gratings were identical. The color of the grating was modulated along different directions in color space around an equal energy white, thus leading to different input contrasts for the L- and M-cones. This allowed us to measure complete detection and identification contours in cone contrast space (Stromeyer, Eskew, Ryu, and Kronauer, ARVO 1991). Under certain spatio-temporal conditions we find that sensitivity is particularly impaired with stimuli near the L-cone null direction. Furthermore, for stimuli having both L- and M-cone contrast sensitivity was determined primarily by the L-cones.

© 1992 Optical Society of America