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