TABLE OF CONTENTS Taste is an important sense that is seldom used in traditional displays. It is the fundamental nature of the underlying sense and the difficulty of implementing unobtrusive devices that have made taste interfaces so difficult.
Humans detect chemical features of food with taste receptor cells. They are assembled into taste buds, which are distributed across the tongue. Although humans can taste a vast array of chemical entities, they evoke few distinct taste sensations: sweet, bitter, sour, salty, and "umami." Distinct taste receptor cells detect each of the five basic tastes (Chandrashekar et al., 2006). Examples of these basic tastes follow:
Sweet: A common sweet substance is sucrose, known as table sugar.
Bitter: A strong bitter taste prevents ingestion of toxic compounds. A small amount of a bitter substance contributes to perceived interesting or good taste/flavor. Caffeine in coffee is an example.
Sour: Sour substances are mostly acids. Vinegar is an example.
Salty: A common salty substance is NaCl, known as table salt.
Umami: This is a Japanese word meaning "savory," and thus applies to the sensation of savoriness. Typical umami substances are glutamates, which are especially common in meat, cheese, and other protein-rich foods (Kawamura & Kare, 1987).
Taste is the last frontier of virtual reality. Taste is very difficult to display because it is a multimodal sensation comprising chemical substance, sound, smell, and haptic sensations.
