Effects of posture on tactile temporal order judgements

. Studies have shown that judgments about the temporal order of two
successive tactile stimuli delivered to left and right index fingers are less
accurate with hands crossed. We were interested whether such temporal order
judgments (TOJs) are affected by physical separation. We describe an
experiment on vibrotactile TOJs with 12 participants. The distance between the
hands was varied orthogonally with crossing of the hands. We found that TOJs
were affected by both the posture of the hands and the spatial separation
between the hands. Performance with hands uncrossed was significantly better
than with hands crossed. As the hands moved closer to the midline, larger
stimulus onset asynchronies were needed for correct report of the temporal
order of the stimuli. The distance effect was obtained in both hands crossed and
uncrossed positions but was more pronounced when the hands were crossed.
We suggest that the effects relate to participants’ internal representation of
proprioceptive and tactile space.