Abstract
Visual illusions have often been reported to have less of an effect on motor responses directed toward the stimulus display than might be predicted on the basis of the magnitude of the illusion. The present research examined whether the rod-and-frame effect (RFE) would display a similar pattern of apparent dissociation between vision and action. In the first experiment, the influences of frame orientation on both the perceived slope of a rod and on open loop pointing responses directed at the ends of the rod were measured. Frames rotated 22.5 deg clockwise and counterclockwise caused the rod to be perceived as tilted in the direction opposite the frame orientation (the RFE). Open loop pointing directed toward the ends of the rod was intermediate to the perceived and physical orientations of the rod, a result consistent with a partial dissociation of vision and action. In the second experiment, pointing responses were obtained either while the display was viewed concurrently or five to twenty seconds following eye closure. The results following the delay were highly similar to the results obtained with concomitant pointing. These findings suggest that during the delay, the motor system maintained a representation of the rod's true orientation to direct action, and did not come to rely to a greater degree on the memory of perceived orientation.