Vibrotactile localization on the abdomen: effects of place and space

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.