Abstract
We introduce a novel visual phenomenon in which two objects traversing distinct motion trajectories seemingly “exchange” their defining features with each other. We demonstrate feature exchange using an ambiguous motion display in which the motion of two translating objects is consistent with the objects colliding or passing through each other (Metzger 1938). We observe that when the two objects have different features (e.g., color, textures, orientations, size, faces), collisions may still be perceived, but the features appear to un-bind from one object and bind to the other. The un-binding and re-binding of the features is quite compelling and occurs with both simple (color, size) and complex (texture, faces) features. This dissociation of feature information and motion trajectory suggests a limited (perhaps non-existent) role of feature information in the spatiotemporal maintenance of object representations. In a series of psychophysical experiments, we use the occurrence of feature exchange as an empirical tool for testing this hypothesis. Methods: Observers reported whether they perceived a pass-through or collision when presented with displays in which the two objects were defined by either the same feature or by one or more different features. We compared the percentage of reported collisions on same-feature and different-feature trials. Results: Although collisions were reported when the two objects differed on one or more feature dimensions (feature exchange), the percentage of these trials was smaller than when the two objects were defined by the same features. Conclusions: Although the existence of feature exchange demonstrates that the features do not fully mediate, they do contribute to, the spatiotemporal maintenance of object representations. Feature exchange depends critically on stimulus parameters, such as contrast relative to the background, differences in relative size of the objects, and whether or not the objects overlap at the point of collision.