The Haptic Moving Room

Abstract

In the moving room paradigm, visually perceived movements of the walls of a room affect the postural sway of individuals in the room. In this experiment, we used a virtual reality (VR) headset to provide visual information about the room, and a tactile device to provide haptic information about the front wall of the room. The tactile device consisted of 48 vibrotactile motors that were pressed against the abdomen and that provided continuous haptic stimulation. In experimental trials, the virtual room oscillated slowly (0.1 Hz) or quickly (0.75 Hz). Participants who stood on a force platform observed the room visually, haptically, or visually and haptically. The registered postural sway reflected the oscillations of the room in all conditions, including the purely haptic ones. The fact that participants coupled their body sway to the room in the visual conditions replicates previous findings that the moving room paradigm can be applied in VR. Although the coupling was less pronounced in the haptic conditions, the existence of this coupling demonstrates that a completely new type of flow information is spontaneously integrated in the elementary and highly practiced perceptual-motor activity of balance control. Applications in the fields of sensory substitution and rehabilitation are discussed.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Note that the time intervals in the experimental and baseline conditions were not identical in these analyses. For example, the interval is 100 s in Figure 2a and 30 s in Figure 2b. If one limits the analysis to a part of the time-series, it is possible to analyze the results using identical intervals in the experimental and baseline conditions. T tests that were identical to the presented ones except for using such equal-length intervals (30 s [3 cycles] for the slow condition and 13.3 s [10 cycles] for the fast condition) were significant with p < 0.001 and d > 1.6 for both frequencies. The analyses reported in the main text are thus the ones with the more conservative results.

2 We should note that in the fast condition it is difficult to determine whether a Fourier component is advanced or delayed with regard to the room. For example, we claim that participants in the fast combined condition were 0.71 s advanced. Given the short period of 1.33 s, however, one could also claim that they were 1.33 – 0.71 = 0.62 s delayed. We opted for the former interpretation because it provides a more consistent pattern over conditions, which is to say, it leads to the view that participants were approximately 0.5 s phase advanced in all conditions with vision.

3 Let us also note that, for the purpose of rehabilitation, we believe that the comfort and ease of use of the equipment of Jeka et al. (1997, 1998), in which the moving object is touched only with a fingertip, cannot be matched by the majority of vibrotactile devices (including, for example, the ones by Peterka et al., 2006, and ours), which must be put on, kept clean, etc.

Additional information

Funding

The contribution of Nicole S. Carver to this research was supported by the National Science Foundation Graduate Research Fellowship under Grant No. 2035701. The development of the haptic device was supported by INDRA and Fundación Universia through their awards Tecnologías Accesibles 2019.