TouchAuthors' Note: We acknowledge support from awards to RLK from the National Science Foundation (IIS‐0964100) and the National Institutes of Health (R01 EY016817) and to SJL from the Canadian Institutes of Health Research (CIHR) during the preparation of this chapter. RLK also acknowledges the support of the Alexander Von Humboldt Foundation.

Abstract

The modality of touch encompasses distinct cutaneous, kinesthetic, and haptic systems that are distinguished on the basis of their underlying neural inputs. The cutaneous receptors are embedded in the skin; the kinesthetic receptors lie in muscles, tendons, and joints; and the haptic system uses combined inputs from both. Topics in this chapter range from sensory-motor phenomena, such as threshold-level responses, to the role of touch in grasping and manipulation, and finally to memory and cognitive processes associated with the haptic system. Haptic perception extracts properties of objects and surfaces that lead to object recognition. Material properties are highly accessible, relative to geometric properties, providing an important contrast between haptics and vision. The haptic system provides a map of space within reach of the body that provides the foundation for recognizing raised two-dimensional patterns and outline drawings. The spatial map is subject to systematic distortion, particularly as a result of the movements used in exploration. Interactions between the haptic system and other modalities, particularly vision, are described with respect to object perception and attention. As with other modalities, the sense of touch gives rise to implicit and explicit forms of memory, which are shared to some extent with visual representations. The chapter concludes with applications of research on touch, including aids for the blind and virtual environments that provide haptic feedback.