From maps to navigation: the role of cues in finding locations in a virtual environment

Detecting the perception of illusory spatial boundaries: Evidence from distance judgments

Spatial boundaries demarcate everything from the lanes in our roadways to the borders between our countries. They are fundamental to object perception, spatial navigation, spatial memory, spatial judgments, and the coordination of our actions. Although explicit spatial boundaries formed by physical structures comprise many of the actual boundaries we encounter, implicit and permeable spatial boundaries are pervasive. The prevailing paradigm for detecting implicit spatial boundaries relies on memory-based distance and location judgments. One possibility is that these biases in spatial memory may be attributable to initial biases in spatial perception, but the extent to which implicit spatial boundaries bias spatial perception remains unknown. An approach for detecting the perception of implicit spatial boundaries would be to infer it through known systematic biases in memory-based distance judgments. We harnessed known biases in memory-based distance judgments to infer perception of spatial boundaries by probing the extent to which distances were overestimated across potential spatial boundaries. Results suggest that participants perceived potential spatial boundaries as illusory spatial boundaries leading to biased judgments of distance. A control group eliminated simple two-dimensional distance cues as responsible for this bias. This bias provides a novel method to detect the perception of illusory spatial boundaries.

Two-category place representations persist over body rotations

We explored a system that constructs environment-centered frames of reference and coordinates memory for the azimuth of an object in an enclosed space. For one group, we provided two environmental cues (doors): one in the front, and one in the rear. For a second group, we provided two object cues: a front and a rear cue. For a third group, we provided no external cues; we assumed that for this group, their reference frames would be determined by the orthogonal geometry of the floor-and-wall junction that divides a space in half or into multiple territories along the horizontal continuum. Using Huttenlocher, Hedges, and Duncan’s (Psychological Review 98: 352-376, 1991) category-adjustment model (cue-based fuzzy boundary version) to fit the data, we observed different reference frames than have been seen in prior studies involving two-dimensional domains. The geometry of the environment affected all three conditions and biased the remembered object locations within a two-category (left vs. right) environmental frame. The influence of the environmental geometry remained observable even after the participants’ heading within the environment changed due to a body rotation, attenuating the effect of the front but not of the rear cue. The door and object cues both appeared to define boundaries of spatial categories when they were used for reorientation. This supports the idea that both types of cues can assist in environment-centered memory formation.