Exploring perceptual processing of ASL and human actions: effects of inversion and repetition priming

In this paper, we compare responses of deaf signers and hearing non-signers engaged in a categorization task of signs and non-linguistic human actions. We examine the time it takes to make such categorizations under conditions of 180° stimulus inversion and as a function of repetition priming, in an effort to understand whether the processing of sign language forms draws upon special processing mechanisms or makes use of mechanisms used in recognition of non-linguistic human actions. Our data show that deaf signers were much faster in the categorization of both linguistic and non-linguistic actions, and relative to hearing non-signers, show evidence that they were more sensitive to the configural properties of signs. Our study suggests that sign expertise may lead to modifications of a general-purpose human action recognition system rather than evoking a qualitatively different mode of processing, and supports the contention that signed languages make use of perceptual systems through which humans understand or parse human actions and gestures more generally.