DESCRIPTION (Applicant's Abstract): The research described in this proposal investigates human spatial memory. The goal of the project is to determine how spatial relations among objects in the environment are represented in and retrieved from memory. The specific aim of the research is to isolate the conditions under which spatial memories are represented in an orientation dependent manner, such that familiar views are more easily recalled and recognized than are unfamiliar views, and the conditions under which spatial memories are represented in an orientation independent manner, such that familiar and unfamiliar views are equally accessible. Several convergent methods will be used. In one line of research, observers will learn the locations of objects in large spaces and then make judgements of relative direction using their memories of the spaces (e.g., "Imagine you are standing at the lamp facing the shoe. Point to the clock".) These studies will manipulate the number of views that observers are allowed to have of the space, the consistency of alternative spatial reference frames, and how the observer is allowed to move in the space when he or she learns it. A second series of experiments uses scene recognition to examine spatial memory. Human observers will see one or more views, differing by rotation in three-dimensional space, of a collection of dots displayed on a graphics monitor, or will commit to memory from one or more perspectives the locations of several objects resting on a surface. The observers will then be given old-new recognition tests in which they must discriminate familiar and novel views of the recently experienced spatial layout from views of other spatial layouts. The familiar and novel views will differ in orientation. A principal goal of this research is to determine when scene recognition performance is orientation dependent and when it is orientation independent. The mechanisms by which novel views are matched to stored views in memory will also be examined. Computation models of scene recognition will be implemented and tested. This basic science provides a foundation for understanding individual differences in spatial ability.