Hemispheric asymmetries for the temporal resolution of brief tactile stimuli

Hemispheric asymmetries for tactile temporal discriminations were examined in 29 dextrals. Vibrations lasting 120 ms were delivered unilaterally to the hands, half of which contained a gap lasting between 6 and 18 ms. Participants indicated whether or not the vibration contained a gap. Visual and auditory research has demonstrated a left hemisphere (LH) advantage for gap detection. However, this research has confounded the effects of hemisphere and hemispace. These effects were dissociated using midline and lateral hand placements. Reaction time (p <.05), response error (p <.1), and response bias (p <.05) measures revealed a LH advantage for gap detection. The asymmetry was reduced in the midline condition for the error data only (p <.1). These results demonstrate that the LH is better able to detect brief temporal events than is the right hemisphere. Hemispace appears to have a limited impact on this asymmetry.