The Role of Gravity in Human Spatial Memory

Research in humans and other animals has shown that different spatial reference systems are used in different spatial tasks and provide the basis for organizing spatial memories. Two groups of 16 subjects each learned the spatial locations of eight different objects surrounding them in the vertical plane while either lying on their sides or their front/back. Their ability to remember the locations was measured in a subsequent test phase. The results showed that subjects were faster and more accurate when they imagined themselves aligned with the vertical axis. Imagined orientations in the horizontal plane led to slower reaction times and less accurate responses, but were markedly better than imagined diagonal orientations. This indicates that humans use the reference direction specified by gravity to structure their spatial memory. Possible implications for the design of spatial displays are discussed.