Psychophysical assessment of the sensory and affective components of touch

Abstract

In this chapter, we address two issues. Initially, we consider how to assess the sensations and emotions that occur through touch. This is not a trivial problem, for there exists a wealth of potentially relevant language that one might use to construct appropriate psychometric instruments. After reviewing the limited number of prior tactile lexicons, we illustrate a method by which we have developed a new lexicon for touch. This ‘Touch Perception Task’ allows the assessment of relevant sensory and emotional components of perception. In the subsequent part of the chapter, we review two classes of devices for the study of touch. These devices either allow tactile stimuli to be delivered in a highly controlled manner, or allow the assessment of the physical interactions between skin and stimulus during tactile perception. The former robotic stimulators are of particular relevance to the study of C-tactile afferents, because they allow stimuli to be presented to hairy skin with velocities that are well- or ill-suited to stimulate such afferents. The other class of force-plate devices tends to be limited to assessing finger-surface interactions, which do not involve C-tactile afferents. However, active touch using the fingers is an important human behavior, which can certainly be replete with emotion. As such, it is important to reconcile C-tactile mediated affect, and the affect that derives from touch devoid of these afferents. Robotic and force-plate devices will both be of utility in this respect.