Shape effects on memory for location.

The participants were 40 students who were briefly presented 32 dot locations, one at a time, and attempted to reproduce each location after a short delay. Half of the participants completed the task with the surrounding shapes being a circle, a horizontal ellipse, and a vertical ellipse; for the other half, the surrounding shapes were a square, a triangle, and a pentagon. Elongation of the task field along an axis led to exaggerated bias along that axis, but the pattern of bias was fairly constant across the shapes. The data were modeled by assuming that bias in estimation was due to the weighting of spatial category prototypes. Modeling indicated that shape affected spacing of prototypes, but there was no evidence that it affected the number of prototypes. These results were consistent with use of a viewer-based frame of reference, with prototypes reflecting four spatial quadrants generated by left-right and up-down distinctions from the viewer's perspective.