Time-to-Contact estimation for visual stimuli approaching the hand

M. Luisa Dematte', Massimiliano Zampini, Francesco Pavani
Poster
Last modified: 2008-05-13

Abstract


In three experiments, we tested whether the multisensory encoding of the space surrounding the hand may play a role in the estimation of the time elapsing before a visual stimulus collides with the hand. Participants were instructed to try and stop a moving disk at the exact moment it collided with a fixed target. The distance (near vs. far) between the target and the participants’ hands was manipulated between trials. Moreover, other additional parameters were considered across experiments: Feedback provided (temporal, i.e., milliseconds before/after collision when the disk was stopped; temporal + semantic, when also incitements were used; temporal + semantic + tactile, when the index fingers were also touched at collision); visibility of the last part of the disk path (visible vs. occluded); response proximity with respect to the target (response far with foot vs. near with hand on screen). The main result revealed that the disk was stopped farther from the target when this corresponded to hand position than when it did not correspond to hand position. Time-to-contact estimation appears to change as a function of the target-hand distance, suggesting a role of peri-hand space encoding in the temporal evaluation of visual stimuli approaching the hand.

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