Vibrotactile localization on the abdomen: Effects of place and space

Abstract

In this study, we explore the conditions for accurate localization of vibrotactile stimuli presented to the abdomen. Tactile orientation systems intended to provide mobility information for people who are blind depend on accurate identification of location of stimuli on the skin, as do systems designed to indicate target positions in space or the status of remotely operated devices to pilots or engineers. The spatial acuity of the skin has been examined for simple touch, but not for the types of vibrating signals used in such devices. The ability to localize vibratory stimuli was examined at sites around the abdomen and found to be a function of separation among loci and, most significantly, of place on the trunk. Neither the structures underlying the skin nor the types of tactor tested appeared to affect localization. Evidence was found for anatomically defined anchor points that provide localization referents that enhance performance even with wide target spacing.

Time-Lag as Limiting Factor for Indoor Walking Navigation

“…45% (5) complained about a generally low vibration intensity on the back. Even if Cholewiak et al [20] stated that belly and back are two anatomical reference points where vibrations are sensed better than on the sides, this did not hold true in our experimental setup, presumably caused by the fact that the tactor elements on the back were only pressed against the skin with low force. (iii) Masking vibration noise: A piece of music delivered via headphones was used to mask the vibration noise in two of the three experiments.…”

“…Tactor Placement: As described by Cholewiak et al [20] vibro-tactile perception is insusceptible to the vertical alignment of actuators on the body in the region from hip to chest, even if the underlying tissue (Epidermis) touched by a certain tactor varies widely and consists either of tendons, bones, muscles, etc. Instead, perception of vibrations is highly influenced by the position of tactor elements around the waist, for instance higher perception is reported for tactors positioned on the anatomical keypoints navel and spinal column, lower perception for vibration elements placed on the sides.…”

“…(i) Frequency Range: We used frequency variation in the range from 200 to 300Hz, since it is known to be perceived best by the Pacinian Corpuscles (PC) (see for instance Cholewiak et al [20] or Riener [6, p. 115f]). Initial studies conducted on higher and lower frequencies confirmed that using frequencies below approximately 150Hz or above 350Hz are difficult to perceive and thus should not be used in Tactograms 6 (ii) Amplitude/Gain Variation: For notifications using different vibration intensities the full range offered by the tactor system has been utilized.…”

Determining the Feasibility of Forearm Mounted Vibrotactile Displays

“…However, as Cholewiak [6] comments, with reference to vibrotactile display systems: "The spatial acuity of the skin has been examined for simple touch but not for the types of vibrating signals used in such devices". Although the body of literature reviewed above is both substantial and informative, due to the fact that vibratory stimuli are not subject to the same perceptual limits as pressure stimuli, basic psychophysical questions relating to the optimal positioning and arrangement of, and stimulus design for, groups of vibrating tactors remains unanswered.…”

Centralizing Bias and the Vibrotactile Funneling Illusion on the Forehead

“…The number and configuration of the vibrotactile stimulators in the tactile display is known to play an important role in vibrotactile localization ability [8] although increasing array granularity does not necessarily improve localization ability [9,10].…”