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Abstract

A series of three sequential picture-picture matching studies compared the effects of a view change on our ability to detect a shape change (Experiments 1 and 2) and the effects of a shape change on our ability to detect a view change (Experiment 3). Relative to no-change conditions, both view changes (30\(^{\circ}\) or 150\(^{\circ}\) depth rotations) and shape changes (small or large object morphing) increased both reaction times and error rates on match and mismatch trials in each study. However, shape changes disrupted matching performance more than view changes for the shape-change detection task (''did the first and second pictures show the same shape?''). Conversely, view changes were more disruptive than shape changes when the task was to detect view changes (''did the first and second pictures show an object from the same view?''). Participants could thus often discriminate between the effects of shape changes and view changes. The influence on performance of task-irrelevant manipulations (view changes in the first two studies; shape changes in the final study) does not support Stankiewicz's (2002; Journal of Experimental Psychology: Human Perception \& Performance, 28, 913-932) claim that information about viewpoint and about shape can be estimated independently by human observers. However the greater effect of variation in the task-relevant than the task-irrelevant dimension indicates that observers were moderately successful at disregarding irrelevant changes.