THE PERCEIVED LOCATION OF A TOUCH SHIFTS WITH EYE POSITION

Vanessa Harrar, Laurence R. Harris, Markus Lappe
Poster
Last modified: 2008-10-27

Abstract


Eye position is known to affect the perceived location of auditory and visual stimuli. Here, we tested for an effect of eye position on the perceived location of a touch on the forearm. Subjects fixated one of four target lights. Between 100 and 450 ms after the target light was turned off, subjects received a touch at one of four locations along the forearm. The forearm was arranged horizontal in front of the subject. Subjects indicated the location of the touch by pointing to its location with their other hand. They then identified the location of the point using illuminated rulers. When subjects fixated to one side of the midline, the perceived position of touches shifted to the same side (maximum displacement: elbow = 1.80 cm; mid-forearm = 3.79 cm; wrist = 3.40 cm). The amount of shift also correlated with variations in tactile acuity along the (variance: elbow = 13.5 cm; mid-forearm: 32.0 cm; wrist = 30.5 cm): locations with less tactile acuity were more affected by eye position. The effect of saccades on tactile localization was also tested. Unlike for visual stimuli, there was no systematic shift in the position of the touch around the time of a saccade.

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