Perception of spatial relations during self-motion
Humans are a highly mobile species, and our chief means of self-movement-locomotion-makes possible many of our uniquely human traits. Of course, the ability to move about would be of little use if we were unable to perceive and monitor our changing position in the environment. Thus, the ability to remain oriented when walking or traveling is crucial, and humans who lack this capacity are virtually helpless. In this chapter, we discuss the means by which people update, or keep track of, their own location and orientation as they move, as well as the locations of objects in the environment. Navigation and locomotion take place across a wide range of spatial scales and time scales, and different instruments and methods are used at different scales. When navigating across country by car, one might follow a remembered series of highways and waypoints or use a dashboard-mounted satellite receiver that provides information about one's current location; when navigating at sea, one might use a similar device or a combination of sextants, clocks, compasses, and charts. By contrast, most people are able to navigate across their living room in the dark without reference to electronic devices and without performing explicit calculations. In this chapter, we focus on spatial updating at this relatively local spatial and temporal scale-that is, when moving among objects in the nearby environment.