These demonstrations stress individual differences, a concept becoming increasingly important in psychological research. Intended for use in undergraduate psychology courses, four demonstrations that illustrate common examples of human variation are described. The demonstrations deal with the following individual differences: taste blindness, relative length of fingers, sex differences in odor detection, and red-green color blindness. Demonstrations are easy to implement. For example, in the activity concerning taste blindness, a phenylthiocarbamide (PTC)-impregnated strip, easily obtained from biology supply labs, is used to test students for taste blindness. Students learn that PTC has a bitter, unpleasant taste for 70 percent of U.S. adults; for the remaining 30 percent PTC is completely tasteless. This phenomenon is a taste dimorphism which is due to variation in a single pair of genes. (RM)