Contour interpolation revealed by a dot localization paradigm.

Contour interpolation mechanisms allow perception of bounded objects despite incomplete edge information. Here, we introduce a paradigm that maps interpolated contours as they unfold over time. Observers localize dots relative to perceived boundaries of illusory, partly occluded, or control stimuli. Variations in performance with dot position and processing time reveal the location and precision of emerging contour representations. Illusory and occluded contours yielded more proficient dot localization than control stimuli containing only spatial cues, suggesting performance based on low-level representations. Further, illusory contours exhibited a distinct developmental time course, emerging over the first 120 ms of processing. These experiments establish the effectiveness of the dot localization paradigm for examining interpolated edge representations, contour microgenesis, and the underlying processing mechanisms.