Figure 1.

Dichoptic stimulus construction. We multiplied two large patches of sinusoidal carrier grating with two raised, sinusoidal modulators (shown for the RE only) (A). Carriers' SFs, drift directions, and speeds were identical. We drifted one modulator at 0.5 Hz (here, LE) and the other at 1.67 Hz (RE) (B). Contrast envelopes were sinusoidal. From trial to trial, we independently varied modulators' SFs and drift directions, enabling estimation of the multiunit RF in each eye. The left and right arrowheads in A mark the spatial locations of the contrast envelopes illustrated in B. The LE contrast envelope is reproduced as a dashed line (B, right) to illustrate the different modulator drift speeds. Arrows and arrowheads are for illustration and did not appear in the stimulus.