Projecting peripersonal space onto a mirror: ERP correlates of visual-tactile spatial interactions.

Chiara Francesca Sambo, Bettina Forster
Poster
Last modified: 2008-05-09

Abstract


Visual-tactile interaction occurs in a privileged way in peripersonal space, namely when visual and tactile stimuli are in spatial proximity. Here, we investigated whether the same principle (i.e. spatial rule) also holds when visual stimuli presented near the body are indirectly viewed in a mirror (i.e. although under this condition the visual image is consistent with stimuli in far space). Participants performed a tactile discrimination task while ignoring task-irrelevant visual stimuli presented simultaneously with tactile stimuli. Visual stimuli were delivered in peripersonal space either at congruent or incongruent locations as touch, and these were observed either directly (experiment ‘near-space’) or as indirect mirror reflections (experiment ‘mirror’). Crossmodal spatial modulations on ERPs were found under both ‘near-space’ and ‘mirror’ conditions; that is ERPs were enhanced in response to tactile stimuli presented with spatially congruent versus incongruent visual stimuli. However, while in the ‘near-space’ condition congruence effects were present from 115 ms after the onset of tactile stimuli, in the ‘mirror’ condition crossmodal spatial modulations only emerged around 160 ms after stimuli onset. These findings suggest that visual stimuli observed in a mirror are recoded as peripersonal stimuli, and furthermore, that the remapping of mirror reflected visual stimuli as peripersonal ones may require an additional stage of processing.

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