Abstract: A PDP11/73 computer and a ONE/80 color graphic display were used to produce green and red-green sinusoidal chromatic gratings. The subjects could manipulate the grating variables and their own responses. by using the keyboard of the computer. In Experiment One, contrast se- nsitivities to green and red-green gratings were measured as a fun- ction of spatial frequency. Both green and red-green contrast sensiti- vity function had similar low-pass characteristics with low-frequency attenuation. In Experiment Two, contrast sensitivities to red-green gra- tings were measured as a function of both the red-green luminance ratio in the grating and the spatial frequencies. The results show that, as the spatial frequency was reduced, the contrast sensitivity increased, and under the same-spatial-frequency condition, the sensitivity was the grea- test when the stimulus had only luminance contrast, the lowest when there were color differences in the stimulus.

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