The interdependence of time and space in somesthesis: The Tau effect reexamined

The Tau effect, whereby the comparative perception of two spaces is altered by the relationship of the temporal intervals associated with them, was examined in the tactile sense. A bilateral stimulus presentation procedure was employed in which the standard and comparison spatial separations were presented alternately to either forearm. The temporal intervals separating the two stimuli delimiting the standard and comparison spatial separations were manipulated over a wide range. Subjects’ judgments of the comparison spatial separation, relative to the standard separation, were altered substantially by varying the temporal relations between the standard and comparison spaces, that is, the Tau effect was obtained. No systematic or substantial laterality effect was found, that is, varying the position of the standard and comparison spaces on the right or left forearm had only a negligible effect.