So far, gustatory information has rarely been studied in relation to computers, even though there are lots of studies on visual, auditory, haptic and olfactory information. This scarcity of research on gustatory information has several reasons. One reason is that gustatory sensation is based on chemical signals, whose functions have not been fully understood yet. Another reason is that perception of gustatory sensation is affected by other factors, such as vision, olfaction, thermal sensation, and memories. Thus, complexity of cognition mechanism for gustatory sensation as described above makes it difficult to build up a gustatory display.