Haptic signals enhance vestibular self-motion perception and reduces vestibular misperception.

This study investigated whether haptic contact modulates vestibular-induced self-motion perception and reduces perceptual errors caused by asymmetric vestibular stimulation. Fifteen healthy right-handed participants underwent asymmetric sinusoidal whole-body rotations about the vertical axis in darkness, consisting of half-cycles with equal amplitudes but different velocities, a paradigm known to induce errors in the localization of a previously memorized visual target. This error, quantified as the final position error (FPE), mainly results from reduced self-motion perception during the slower half-cycle. Under vestibular-only conditions, a large FPE was observed after four cycles. To investigate the influence of haptic input, participants touched a spatially fixed object with either the right or the left hand during asymmetric rotation The object was placed either at the body midline or in the right or left hemispace. Haptic contact significantly reduced the vestibular induced FPE, by enhancing perception of the slow self-motion, likely through proprioceptive input from the upper limb. The strongest improvement was observed when participants used the right hand to contact an object in the right hemispace, with smaller reductions occurring with right-hand contact at the midline or in the left hemispace. The effect was less pronounced with left-hand contact. Importantly, although haptic contact markedly reduced vestibular-induced perceptual errors, it did not abolish the underlying vestibular adaptive process responsible for the FPE. In conclusion, haptic contact significantly mitigates vestibular-induced self-motion misperception, with effects depending on both hand laterality and contact location.