Abstract
Purpose. Despite retinotopic ambiguities, the visual system is capable of establishing correctly feature-object relationships. By using the Ternus-Pikler display, we have shown that perceived motion correspondences serve as the medium for non-retinotopic attribution of features to objects. The purpose of this work was to assess whether perceived motion correspondences provide a sufficient condition for feature attribution.
Methods. The stimulus consisted of a first frame containing three vertical lines, a blank ISI, and a second frame containing the three lines shifted to the right by one inter-line distance. A vernier offset was inserted to the second element of the first frame. Observers' task was to report the direction of the vernier offset for a pre-designated line in the second frame. We introduced a static “barrier” (a long vertical line) between the elements of the Ternus-Pikler display.
Results. We show that a barrier can prevent feature attribution. The assessment of perceived motion in the presence of the barrier stimulus indicates that the effect of the barrier on feature attribution is not by disrupting the motion percept itself, but instead by interfering with the process of feature attribution. The interference of the barrier with feature attribution depends in a complex way on the contrast, spatial, and temporal characteristics of the barrier.
Conclusions. Perceived motion correspondences do not provide a sufficient condition for feature attribution. Parametric properties of barrier interference indicate that this interference is not merely due to the barrier serving as a spatiotemporal reference. Instead, we suggest that feature attribution results from a non-retinotopic remapping that takes into account both dynamic and static characteristics of stimuli.