Effects of orientation adaptation on motion perception

Purpose. In a previous investigation, we found that attention directed to a stationary Gabor patch in the center of the visual field can bias the perceived direction of plaid motion in the periphery (Caudek & Domini, 2001). Consistently with the interpretation that has been provided to those previous results, here we tested the following related hypothesis: Adaptation to a stationary Gabor patch affects differently subsequent motion sensitivity in the parallel or orthogonal directions relative to the Gabor's orientation. Methods. In each trial, observers underwent adaptation (4 s) to a 0°, 45° or 315° oriented Gabor patch. Immediately after adaptation, a stochastic motion stimulus (Williams & Sekuler, 1984) was presented for 140 ms. In half of the trials a proportion of dots (i.e., ‘signal’ dots) moved in a coherent direction whereas each of the remaining (‘noise’) dots moved in a random direction. In the other half of the trials all dots were noise dots. Coherent motion was simulated in the 45°, 135°, 225°, 315° directions. The task was to discriminate between noise and signal-plus-noise trials. Results. Consistently with our hypothesis, motion sensitivity differed in the orthogonal and parallel directions relative to the Gabor orientation. In particular, we found a lower motion sensitivity in the direction parallel to the Gabor orientation. Conclusions. The present results indicate that adaptation to a stationary stimulus can subsequently affect motion perception, and are consistent with the feature similarity model of Treue and Trujillo (1999).