Touch and Haptics

Abstract

This chapter describes the psychophysics of touch—how tactile abilities and perceptions are measured, and what those measurements reveal about the somatosensory system. The ability to discern spatial aspects of tactile stimuli, such as how many are present and where they are on the skin, has been extensively studied: A key finding in this area is that resolution acuity predicts performance on a range of other tasks. Researchers have also examined temporal aspects of touch, especially through the use of vibration. Studies using masking and other paradigms have revealed the existence of vibrotactile channels associated with mechanoreceptor classes. Signals in these channels encode the intensity and frequency of vibratory stimuli, and contribute to the perception of textured surfaces. Many tactile stimuli involve temporal changes in spatial aspects of stimulation; an understanding of how these are perceived requires that a variety of spatio‐temporal distortions be taken into account. The chapter ends with a discussion of haptics (active touch) by which an attentive observer explores an object to discover its properties and identity. Kinesthetic as well as cutaneous signals play a role in this search for information, but how they are combined is a process that is only beginning to be understood.

Vibrotactile perception: examining the coding of vibrations and the just noticeable difference under various conditions

“…Human mechanoreceptors found in the skin mediate tactile perception through mechanical stimulation obtained by direct contact with external stimuli in the environment ( [3]) or, in the case of telemanipulation, via contactors present in tactile interfaces which are used to feed back the tactile properties from the remote environment (e.g. [4][5][6]).…”

Tactile orientation constancy: Do proprioception and attention affect the tactile vertical?1

“…The aim of this study was to learn how the perceived orientation of a tactile stimulus is affected when the body site to be stimulated changes its orientation in space. Although there have been hundreds of studies that deal with various spatial aspects of touch, such as acuity, localization, distance, and motion, relatively little attention has been paid to the perceived orientation of tactile stimuli (see Greenspan & Bolanowski, 1996; Hollins, 2002 for reviews of tactile perception). A notable exception is a study by Anstis and Tassinary (1983), who demonstrated that the perceived orientation of an edge that stimulates the lips varies with distortion of the lips.…”