[Vision influences on tactile discrimination of grating orientation]

Studies have revealed a number of instances of cross-modal spatial interactions between vision and touch. However, few studies have addressed the possible role of cross-modal interactions in the identification of objects. This study assessed whether tactile pattern perception is affected by adding a concurrent visual stimulus. Participants were required to discriminate the orientation of tactile grating patterns, which were presented in synchrony or asynchrony with a task-irrelevant visual grating pattern that had the same or different orientation as the tactile pattern. The results demonstrated that accuracy in discriminating grating orientation was reduced when the tactile and visual gratings differed in orientation, but only when the two modalities were presented concurrently. The findings are discussed in terms of multisensory integration for processing of shape information.