The Tactile Modality: A Review of Tactile Sensitivity and Human Tactile Interfaces

Even though vision is only one modality humans use to interact with their environment, most people consider it to be the most important. Hearing also is viewed as necessary for interpreting environmental stimuli. In contrast, touch, smell, and taste are largely ignored as being essential to humans' interaction with the environment. The brain seldom processes environmental information sequentially using successive sensory modalities; rather, it simultaneously processes stimuli from several or all of the sensory modalities. Because humans have a limited capacity to receive, hold in working memory, and cognitively process information taken from the environment, the use of one sensory modality to convey information within a system can overload that modality. Multimodal systems can help to alleviate overload for any one modality, and such systems have been favorable in showing that the touch or tactile modality can be used as an independent input modality to convey information to the user, or as a redundant modality to increase information prominence of the visual and auditory modalities. The purpose of this review, which reflects work that occurred before mid-2006, is to discuss the tactile modality, specifically measures of tactile sensitivity for the human body, capabilities and limitations of the tactile modality, and applications of human tactile interfaces. Compared to other areas of the body, tactile research for the head and interfaces for the head is sparse. Therefore, a secondary concern of this review is to highlight this gap in the tactile literature.