Effects of stimulus orientation on the identification of common polyoriented objects

Experimental evidence has shown that the time taken to recognize objects is often dependent on stimulus orientation in the image plane. This effect has been taken as evidence that recognition is mediated by orientation-specific stored representations of object shapes. However, the factors that determine the orientation specificity of these representations remain unclear. This issue is examined using a word-picture verification paradigm in which subjects identified line drawings of common mono- and polyoriented objects at different orientations. A detailed analysis of the results showed that, in contrast to mono-oriented objects, the recognition of polyoriented objects is not dependent on stimulus orientation. This interaction provides a further constraint on hypotheses about the factors that determine the apparent orientation specificity of stored shape representations. In particular, they support previous proposals that objects are encoded in stored representations at familiar stimulus orientations.