Investigating Movement-Related Tactile Suppression Using Commercial VR Controllers

Abstract

When we perform a goal-directed movement, tactile sensitivity on the moving limb is reduced compared to during rest. This well established finding of movement-related tactile suppression is often investigated with psychophysical paradigms, using custom haptic actuators and highly constrained movement tasks. However, studying more naturalistic movement scenarios is becoming more accessible due to increased availability of affordable, off-the-shelf virtual reality (VR) hardware. Here, we present a first evaluation of consumer VR controllers (HTC Vive and Valve Index) for psychophysical testing using the built-in vibrotactile actuators. We show that participants’ tactile perceptual thresholds can generally be estimated through manipulation of controller vibration amplitude and frequency. When participants performed a goal-directed movement using the controller, vibrotactile perceptual thresholds increased compared to rest, in agreement with previous work and confirming the suitability of unmodified VR controllers for tactile suppression research. Our findings will facilitate investigations of tactile perception in dynamic virtual scenarios.

How visuomotor predictability and task demands affect tactile sensitivity on a moving limb during object interaction in a virtual environment

“…This experiment extends previous work showing that off the shelf VR equipment can be used to investigate tactile suppression using a psychophysical task [ 24 ]. It also extends previous research on tactile suppression to more naturalistic settings by using large-scale movements in a dynamic interaction task performed in a complex visual environment.…”

“…In order to probe tactile sensitivity, we delivered brief vibrations to the palm of the right hand via the VR controller [ 24 ]. The vibration was presented at 250 Hz for 50 ms at one of eight possible intensities (0.00099, 0.0033, 0.0066, 0.0099, 0.033, 0.066, 0.099, 0.33 arbitrary units) plus a no-vibration condition.…”

“…In this study, we investigated tactile suppression when interacting with dynamic objects that vary in the predictability of their behaviour. We exploited the advantages of virtual reality (VR) allowing us to systematically change the object's dynamics and to assess hand motion and tactile sensitivity using the VR controllers [24]. As experiments performed in VR have been associated with higher cognitive load compared to tasks performed on a monitor or in real-world environments [25][26][27], probably due to increased visual complexity and unfamiliar object dynamics during interaction, we also assessed task load across our experimental conditions which varied in the dynamics of the interaction target.…”

“…Based on previous findings [ 2 , 5 , 24 ], we hypothesized that the probing stimuli would be perceived as weaker during movement relative to a resting Baseline condition. If the strength of tactile suppression reflects the weighing of predictive and somatosensory feedback signals [ 5 ], tactile suppression should be weaker when the object changes orientation, which may require facilitation of somatosensory feedback processing to successfully adjust the movement.…”