Subjects made matches to isolated squarewaves and to mixture gratings that consisted of sums of squarewaves. Specifically, they set matches to the two differently colored bars of a squarewave grating, and the four differently colored bars of a mixture grating.
We constructed isolated squarewave gratings of 1, 2 and 4 c/deg. The squarewaves were created in one of three color directions. The complementary bars in the grating appeared greenish yellow/purple, turquoise/rose, or orange/light blue