Intrinsic array structure is neither necessary nor sufficient for nonegocentric coding of spatial layouts

Mou and McNamara (2002) have recently theorized that nonegocentric reference frames (viz., intrinsic reference frames, based on the spatial structure of a configuration of objects) are used to organize spatial relationships in memory. The theory has not made claims about whether the intrinsic structure of a stimulus array is necessary or sufficient for such nonegocentric coding. We demonstrate that salient intrinsic axes in a layout of objects are neither necessary nor sufficient for people to use a nonegocentric reference frame in organizing spatial memory. In Experiment 1, participants were successfully instructed to adopt a nonegocentric preferred direction in memory for an array of objects with no salient intrinsic reference axes. In Experiment 2, with no instructions, participants adopted an egocentric preferred direction for an array with a salient intrinsic axis. These results suggest that physically salient array structure exerts a minimal influence in the coding of spatial memory through nonegocentric reference frames.