A polarity effect in misoriented object recognition: The role of polar features in the computation of orientation-invariant shape representations

This study investigated the contribution of polar features and internal shape axes to misoriented object recognition. A recognition memory paradigm was used to examine the effects of stimulus orientation on the recognition of previously memorized 2-D novel objects. In contrast to some recent reports, Experiment 1 showed that orientation-invariant performance can be found from the outset of testing with objects containing a salient axis of symmetry. In Experiments 2 and 3 it was found that the removal of a single salient polar feature, while preserving the axis of elongation, was sufficient to increase stimulus orientation time costs. This polarity effect suggests that polar features, and shape axes, play a role in the computation of orientation-invariant shape representations. It is proposed that shape axes facilitate the localization of polar features, which, in turn, are used to resolve the polarity of shape representations during recognition.