T. Barkowsky et al. (Eds.): Spatial Cognition V, LNAI 4387, pp. 59–75, 2007. © Springer-Verlag Berlin Heidelberg 2007 Remembering Places in Space: A Human Analog Study of the Morris Water Maze Sylvia Fitting, Gary L. Allen, and Douglas H. Wedell Department of Psychology, University of South Carolina, Columbia, SC 29208 USA fitting@sc.edu Abstract. We conducted a human analog study of the Morris Water Maze, with individuals indicating a remembered location in a 3 m diameter arena over different intervals of time and with different memory loads. The primary focus of the study was to test a theory of how varying cue location and number of cues affects memory for spatial location. As expected, memory performance as measured by proximity to the actual location was negatively affected by increasing memory load and delay interval and decreasing number of cues. As memory performance decremented, bias effects increased and were in accordance with the cue-based memory model described by Fitting, Wedell and Allen (2005). Specifically, remembered locations were biased toward the nearest cue and error decreased with more cues. These results demonstrate that localization processes that apply to small two-dimensional task fields may generalize to a larger traversable task field. Keywords: Categorical coding, environmental cues, Morris Water Maze, spatial cognition, place memory. 1 Introduction Remembering where objects are located is a common and adaptive activity across species. Several variations on this task may arise from variations in key environmental constraints. For example, the environmental space may be small and two dimensional, such as when remembering a location on the surface of one’s computer monitor; moderately large and traversable, such as when remembering where one put one’s keys in a room; or much grander in scale and scope, such as when one remembers the location of a residence in the countryside. In addition to the size variable, shape of the environment is a critical factor. For example, several researchers have shown how geometric facets of the environment guide memory for location (Cheng, 1986; Hermer & Spelke, 1994), with some positing that geometric coding of spatial location may constitute a primitive module for processing this information (Gallistel, 1990). The existence of clearly defined paths is another shape constraint likely to influence memory for location, as numerous studies have documented route specific learning (Siegel & White, 1979). In addition to size and shape, the surface features of the environment may be critical. Such surface features may serve as proximal or distal cues for coding memory for location (Egan, 1979).