TO WHAT EXTENT DO UNIQUE PARTS INFLUENCE RECOGNITION ACROSS CHANGES IN VIEWPOINT

We investigated how varying the number of unique parts within an objec t influences recognition across changes in viewpoint. The stimuli were shaded objects composed of five three-dimensional volumes linked end to end with varying connection angles. Of the five volumes, zero, one, three, or five were qualitatively distinct (e.g,, brick vs. cone), th e rest being tubes. Sequential-matching and naming tasks were used to assess the recognition of these stimuli over rotations in depth. Three ,major results stand out. First, regardless of the number of distinct parts, there was increasingly poorer recognition performance with incr easing change iii viewpoint. Second, the impact of viewpoint change fo r objects with one unique part was less than that for the other object s. Third, additional parts beyond a single unique parr produced strong viewpoint dependency comparable to that obtained for objects with no distinct parts. Thus, visual recognition may be explained by a view-ba sed theory in which viewpoint-specific representations encode both qua ntitative and qualitative features.