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Abstract

In apparent motion displays, the remembered final position of a translating object is often displaced in the direction consistent with its implied path of motion. In literature, this forward displacement is known as representational momentum, suggesting an underlying dynamical process for perceptual representations. There is only little evidence for representational momentum in transforming targets. In a series of experiments, we investigated whether representational momentum can be generalized to form transformations such as rotation and morphing. Observers saw a series of three sequentially presented images (SOA of 250ms each), implying either depth rotation or morphing, followed by a test image, which they had to adjust to match the last presented (third) image by pressing to keys. Stimuli were rendered from 3D-generated models of either a simple cuboid model or a complex face model. Responses were measured as displacement from the position of the last presented image. For the rotation transformation we report a significant backward displacement using the complex object. There was no significant effect using the simple object. For the morphing transformation a significant backward displacement was found using the complex object and a significant forward displacement using the simple object. In addition, we examined how the observer’s performance relates to the canonical perspective (for rotation transformations) and to the prototypical exemplar (for morphing transformations), which was determined by the observer before the experiment. For the rotation sequences, we calculated the distance from the last presented image to the canonical perspective for each trial and correlated it with the corresponding memory distortion. We found a negative correlation for the complex object, but no significant correlation for the simple object. Accordingly, we calculated the distance from the last presented image to the prototypical exemplar of the morphing sequences and determined the correlation with the corresponding memory distortion. Again, the complex object showed a negative correlation, whereas the simple object revealed a positive correlation. Representational momentum, as demonstrated for translating objects, has not been found for transforming objects in general. Representational momentum was only detected when simple objects were morphed. It did not occur for complex objects. Remembering the final image of rotating and morphing objects seem not related to remembering the final position of a translating target. Canonicalness and prototypicality seem to influence remembering the final shape or perspective of an object. With increasing distance from the canonical perspective or the prototypical exemplar memory distortion increases.