Duplexity Theory of Taste

Abstract

When two different taste stimuli are presented, one to the left and the other to the right side of the tongue, they may add together to a sensation in the middle of the tongue, or they may stay separated. This phenomenon can be used to show that the four primary taste sensations seem to form two well-differentiated groups. Warm and cold stimuli act similarly to the four primary taste stimuli, thus separating the sensations on the tongue into two groups: bitter, warm, sweet; and sour, cold, salty.