The display systems that we have described rely primarily on vision, and, to a limited extent, sound. It is important to recognize that a sense of immersion is a function of more than vision and sound-it involves all of the senses, including touch, smell, taste, and body movement. Outside the field of geography, sophisticated systems have been developed that incorporate multiple senses. For instance, the $50 million National Advanced Driving Simulator (NADS) housed at the University of Iowa can be used to simulate the "feel" of driving (http://www.nads-sc.uiowa.edu/; Samuels 1999), and thus can provide a safe means of evaluating the effects of alcohol, drugs, and fatigue on driving Although geographers probably do not need such sophisticated systems, work needs to be done to explore the roles of the other senses in GeoVEs. Some of the senses currently being explored include sound touch, hand gestures, and body movements. Because developments in these areas are relatively recent, we consider them in Chapter 26