Sample of Current Projects

The role of environmental geometry in maintaining spatial orientation was measured in immersive virtual environments using a spatial updating task (requiring maintenance of orientation during locomotion) within rooms varying in rotational symmetry (the number of room orientations providing the same perspective).  Spatial updating was equally good in trapezoidal, rectangular and square rooms (1-fold, two-fold and four-fold rotationally symmetric, respectively) but worse in a circular room (∞-fold rotationally symmetric).  This contrasts with reorientation performance, which was incrementally impaired by increasing rotational symmetry.  Spatial updating performance in a shape-changing room (containing visible corners and flat surfaces, but room shape changed over time) was no better than performance in a circular room, indicating that superior spatial updating performance in angular environments was due to remembered room shape, rather than improved self-motion perception in the presence of corners and flat surfaces.

Previous research has uncovered three primary cues that influence spatial memory organization: egocentric experience, intrinsic structure (object-defined), and extrinsic structure (environment-defined).  In the present experiments, we assessed the relative importance of these cues when all three are available during learning.  Participants learned layouts from two perspectives in immersive virtual reality.  In Experiment 1, axes defined by intrinsic and extrinsic structures were in conflict and learning occurred from two perspectives, each aligned with either the intrinsic or extrinsic structure.  Spatial memories were organized around a reference direction selected from the first perspective, regardless of its alignment with intrinsic or extrinsic structures.  In Experiment 2, axes defined by intrinsic and extrinsic structures were congruent, and spatial memories were organized around reference axes defined by those congruent structures rather than the initially experienced view.  Findings are discussed in the context of spatial memory theory as it relates to real and virtual environments.

We are currently investigating the extent to which spatial memories acquired through language are similar to those acquired through vision. In one experiment, participants read route texts in which they learned object locations while imagining walking through a baseball field. The described path was aligned or misaligned with the familiar shape of the infield. The question of interest was whether alignment between the path and the familiar shape of the environment would influence spatial memories acquired from language in the same way that it affects spatial memories acquired from vision (e.g., Shelton & McNamara, 2001). In on-going experiments, participants are learning the locations of objects in a real baseball field, Hawkins, the home field of the Vanderbilt Commodores.

Recent experiments examined the use of representations of self-to-object or object-to-object spatial relations during locomotion. Participants learned geometrically regular or irregular layouts of objects while standing at the edge or in the middle, and then pointed to objects while blindfolded in three conditions: before turning (baseline), after rotating 240 degrees (updating), and after disorientation (disorientation). The internal consistency of pointing in the disorientation condition was equivalent to that in the updating condition when participants learned the regular layout.  The internal consistency of pointing was disrupted by disorientation when participants learned the irregular layout. However when participants who learned the regular layout were instructed to use self-to-object spatial relations, the effect of disorientation on pointing consistency appeared. When participants who learned the irregular layout at the periphery of the layout were instructed to use object-to-object spatial relations, the effect of disorientation disappeared. These results suggest that people represent both self-to-object and object-to-object spatial relations, and primarily use object-to-object spatial representation in a regular layout and self-to-object spatial representation in an irregular layout.

Two experiments explored the role of environmental cues in maintaining spatial orientation (sense of self-location and orientation) during locomotion.  Of particular interest was the importance of geometric cues (provided by environmental surfaces) and featural cues (non-geometric properties provided by striped walls) in maintaining spatial orientation.  Participants performed a spatial updating task within virtual environments containing geometric or featural cues that were ambiguous or unambiguous indicators of self-location and orientation.  Cue type (geometric or featural) did not affect performance, but the number of environmental cues and the ambiguity of those cues did affect performance.  Gender differences, which are interpreted as a proxy for individual differences in spatial skills and/or experience, highlight the interaction between cue quantity and ambiguity.  When environmental cues were ambiguous, men stayed oriented with one or two cues, whereas women only stayed oriented with two ambiguous cues.  When environmental cues were unambiguous, women stayed oriented with one cue.

Spatial memory research with humans and non-human species suggests that geometric information in extended surfaces (such as the walls of a room) provides particularly useful information in navigation and reorientation, compared to geometric information in discrete surfaces (such as the objects within a room). Participants in these experiments learned the configuration of a room with four corners and the configuration of four objects within the room while standing in a fixed position. The configurations were either rectangular (Experiment 1) or irregular (Experiment 2). In neither experiment was the room configuration recalled more accurately than the object configuration. In addition, spatial memories for rooms and for objects were both affected by manipulations of learning viewpoint and imagined heading during recall. These results suggest that extended surfaces and object layouts are represented similarly in human memory and serve similar roles in spatial functioning.

May (2004) suggested that the difficulty of imagined perspective switches is partially caused by interference between the sensorimotor (actual) and to-be-imagined orientation.  Here, we demonstrate a similar interference, even if participants are in a remote room and don’t know their physical orientation with respect to the to-be-imagined orientation.  Participants learned 15 target objects located in an cluttered office from one orientation (0°, 120°, or 240°).  Participants were blindfolded and disoriented before being wheeled to an empty test room of similar geometry. Participants were seated facing 0, 120°, or 240°, and asked to perform judgments of relative direction (e.g., imagine facing “pen”, point to “phone”).  Performance was facilitated when participants’ to-be-imagined orientation in the learning room was aligned with the corresponding orientation in the test room.  This suggests that merely being in an empty room of similar geometry can be sufficient to automatically re-anchor one’s representation and thus produce orientation-specific interference.