Boundaries of tactile acuity when exploring surfaces

Abstract

Our sense of touch enables us to perform dexterous manipulation and to extract features of objects and textures along a large number of sensory dimensions. Tactile discrimination abilities vary greatly according to the body site, and is maximal in the hand; due to its significant role in our daily interactions and communication. A large number of studies have focused on the boundaries of tactile perception with the fingers, which are heavily involved in discriminative touch to distinguish both gross and fine features. In this review, we will explore interactions in which touch is extremely accurate and interactions that induce unprecise, illusory tactile perceptions, focusing mainly on the glabrous, non-hairy skin of the hand and fingers, due to its importance in interacting with the world. We compare the perception of tactile dimensions over various processes, including different dimensions in touch like roughness, stickiness, and texture, as well as the impact of exploring surfaces with more than one finger. We also cover the potential to include temperature in haptics and its importance in shaping tactile interactions. The research from perceptual studies in humans is compared in terms of neurophysiological studies and computational models of touch, where it is important to understand both peripheral and central coding of touch to apply the findings in haptic devices. Finally, we highlight where future work can add to knowledge and lead to tactile and haptic applications, such as in the clinical domain for better diagnostics, in industries like the cosmetic and car manufacturing sectors to improve consumer usage, and the extension into bio-inspired sensors for robotic sensing and e-skins.