Relatively little has been done to date on simulating taste electronically. Figure 13.6 shows one recent example, in which electrodes are placed over and under the tongue to provide stimulation that simulates the main taste types. In another work, taste illusions are formed by accompanying eating with incorrect visual and olfactory cues . It is generally difficult to develop gustatory interfaces for VR without actually causing people to eat food during the experience. There are clearly health and hygienic issues as well.