Vertical illusory self-motion through haptic stimulation of the feet

Abstract

Circular and linear self-motion illusions induced through visual and auditory stimuli have been studied rather extensively. While the ability of haptic stimuli to augment such illusions has been investigated, the self-motion illusions which primarily are induced by stimulation of the haptic modality remain relatively unexplored.In this paper, we present an experiment performed with the intention of investigating whether it is possible to use haptic stimulation of the main supporting areas of the feet to induce vertical illusory self-motion on behalf of unrestrained participants during exposure to a virtual environment depicting an elevator. The experiment was based on a within-subjects design where all participants were subjected to identical visual and auditory stimuli. The participants experienced a total of four conditions. For three of the conditions a different signal was used to generate the haptic feedback while the final condition included no haptic feedback. Analysis of self-reports were used to assess the participants' experience of illusory self-motion. The results indicate that such illusions are indeed possible. Significant differences were found between the condition including no haptic feedback and the remaining three conditions.

Haptically Induced Illusory Self-motion and the Influence of Context of Motion

“…The experiment described in the current paper should to a large extent be considered as a continuation of work described by Nordahl et al [7] since it was performed with the intention addressing these three claims. Moreover this implies that it was an implicit goal to determine whether it is possible to induce horizontal self-motion illusions within the context of a virtual environment by haptically stimulating the feet of unrestrained participants.…”

“…The dominance of vertical self-motion illusions in the experiment described by Nordahl et al [7] is arguably a testament to the influence of top-down factors. The participants' past experiences entailed that the context of motion (the virtual elevator) may have coloured their interpretation of the implicit motion cues delivered through auditory and haptic feedback.…”

“…Research on haptically induced illusory self-motion is rather scarce and with a few exceptions [14,7] the experiments have generally focused on whether this form of stimuli positively influences an illusion of movement facilitated by stimulation of another modality [12,17].…”

“…Inspired by the study described by Roll et al [14], Nordhahl and colleagues [7] performed an experiment intended to determine if it is possible to facilitate vertical illusory self-motion on behalf of unrestrained participants exposed to a immersive VE by haptically stimulating the main supporting areas of their. The dominance of vertical self-motion illusions in the experiment described by Nordahl et al [7] is arguably a testament to the influence of top-down factors.…”

“…The signal used to control the haptic feedback was a sawtooth waveform. This signal was chosen based on the findings of Nordahl et al [7]. The intention was for the auditory and haptic stimuli to serve as implicit motion cues.…”