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 ha s been taken as evidence that recognition is mediated by orientation-specif ic stored representations of object shapes. However, the factors that deter mine the orientation specificity of these representations remain unclear. T his issue is examined using a word-picture verification paradigm in which s ubjects identified line drawings of common mono- and polyoriented objects a t different orientations. A detailed analysis of the results showed that, i n contrast to mono-oriented objects, the recognition of polyoriented object s is not dependent on stimulus orientation. This interaction provides a fur ther constraint on hypotheses about the factors that determine the apparent orientation specificity of stored shape representations. In particular, th ey support previous proposals that objects are encoded in stored representa tions at familiar stimulus orientations.