Abstract
Purpose: two-component moving plaids may contain two pattern direction solutions, (Bowns, 1996), however, they are perceived to move in a single direction. We asked the following question: if a subject adapts to the perceived direction will the plaid be perceived in the other direction? Method: subjects were first tested to check their perceived direction of a two-component plaid previously reported to move in either the vector sum direction or the Intersection of Constraints direction (IOC). Subjects then adapted to their perceived direction using either a) a single grating moving in their perceived direction, or b) a plaid moving in their perceived direction. Plaids were used as a control to ensure that the orientation of each of the components in the adapting plaid was a minimum of 40 deg. orientation away from the components in the test plaid stimulus. Results: if subjects perceived a moving plaid in the IOC direction, after adaptation they perceived the plaid in the vector sum direction. If subjects perceived a moving plaid in the vector sum direction, after adaptation they perceived the plaid in the IOC direction. Conclusions: we believe that our results provide firm evidence for the existence of multiple solutions competing for perceived pattern direction, the balance of which can be shifted following brief adaptation. These results cannot be explained in terms of adaptation to individual components. It is interesting to note that pattern direction can be adapted using both single component direction as well as plaid component direction.