Grasping adjustments to haptic, visual, and visuo-haptic object perturbations are contingent on the sensory modality

Abstract

Haptics provides information about the size and position of a handheld object. However, it is still unknown how haptics contributes to action correction if a sudden perturbation causes a change in the configuration of the handheld object. In this study, we have occasionally perturbed the size of an object that was the target of a right-hand reach-to-grasp movement. In some cases, participants were holding the target object with their left hand, which provided haptic information about the object perturbation. We compared the corrective responses to perturbations in three different sensory conditions: visual (participants had full vision of the object, but haptic information from the left hand was prevented), haptic (object size was sensed by the left hand and vision was prevented), and visuo-haptic (both visual and haptic information were available throughout the movement). We found that haptic inputs evoked faster contralateral corrections than visual inputs, although actions in haptic and visual conditions were similar in movement duration. Strikingly, the corrective responses in the visuo-haptic condition were as fast as those found in the haptic condition, a result that is contrary to that predicted by simple summation of unisensory signals. These results suggest the existence of a haptomotor reflex that can trigger automatic and efficient grasping corrections of the contralateral hand that are faster than those initiated by the well-known visuomotor reflex and the tactile-motor reflex. NEW & NOTEWORTHY We show that online grip aperture corrections during grasping actions are contingent on the sensory modality used to detect the object perturbation. We found that sensing perturbations with the contralateral hand only (haptics) leads to faster action corrections than when object perturbations are only visually sensed. Moreover, corrections following visuo-haptic perturbations were as fast as those to haptic perturbations. Thus a haptomotor reflex triggers faster automatic responses than the visuomotor reflex.

Integration of haptics and vision in human multisensory grasping

“…These peak grip aperture changes were very consistent across participants (Figure 5a, b, and c). The result that the peak grip aperture is smallest in VH replicates and extends previous findings (Camponogara & Volcic, 2019a, 2019b), and supports the idea that the simultaneous availability of visual and haptic inputs leads to a substantial multisensory advantage (approximately 5 mm and 10 mm smaller average peak grip aperture compared to V and H, respectively).…”

“…The study presented here was designed to investigate the role of visual and haptic cues in visuo-haptic multisensory grasping. The results show that the availability of both vision and haptics produced faster reach-to-grasp movements with considerably narrower grip apertures than in the unisensory conditions (vision-only or haptics-only) extending our previous findings (Camponogara & Volcic, 2019a, 2019b) over a wide range of object sizes and object positions. Critically, when full vision was coupled with the haptic position cue only (VHP), grasping movements were indistinguishable from those found in the full visuo-haptic condition (VH) in which also the haptic size cue was available.…”

“…Based on previous research (Camponogara & Volcic, 2019a, 2019b, we expect the multisensory (VH) condition to exhibit faster grasping movements with smaller peak grip apertures than the V and H unisensory conditions. Whereas all three integration models predict improved grasping performance compared to when objects are only visually or haptically sensed, the comparison between the two multisensory conditions (VH vs. VHP) is instead crucial to distinguish among the full integration, size integration and position integration models.…”

“…However, movements toward haptically sensed objects are usually slower and show a wider grip aperture compared to movements directed toward visually detected objects (Camponogara & Volcic, 2019b; Pettypiece, Culham, & Goodale, 2009; Pettypiece, Goodale, & Culham, 2010). Importantly, the simultaneous availability of vision and haptics leads to faster movements with narrower grip apertures compared to when objects are only visually or haptically sensed (Camponogara & Volcic, 2019a, 2019b). Thus, haptics can effectively integrate with vision to plan and execute grasping actions, but how does each sense contribute to this multisensory-motor transformation is still poorly understood.…”

Using Immersive Virtual Reality to Examine How Visual and Tactile Cues Drive the Material-Weight Illusion

“…Integration of visual and haptic cues (multisensory integration) can resolve perceptual ambiguities and enhance perceptual judgements (Camponogara & Volcic, 2019;Lalanne & Lorenceau, 2004;Wijntjes et al, 2009). The exact nature of this integration is dependent on the reliability and adaptive contribution of each modality in the context (Burke et al, 2006).…”