Abstract:

It is widely accepted that spatial updating is online, and supported by sensation and perception. However, recent studies suggest that people may update the retrieved offline spatial memory in some conditions. For example, after learning a spatial layout, Kelly, Avraamides, and Loomis (2007) had participants walk to a neighboring (novel) room and imagine that they were standing in the center of the learned environment. Next, the participants rotated in place to face a direction different from the learned perspective. After that, they performed direction judgments from imagined perspectives that were aligned or misaligned with their actual facing direction. Sensorimotor alignment effects (i.e., the advantage for spatial judgments from imagined perspectives aligned with the body) may have been caused by instructions that encouraged participants to imagine themselves immersed in the learning environment or by visual similarities between the testing and learning environments. This phenomenon is explained as linking the retrieved offline spatial memory to the online spatial updating system (Avraamides & Kelly, 2008). However, because the imagined environment was parallel with the real environment, and because there was no manipulation check to verify whether the participants lost their online representation, it was also possible that the participants still held their online representation and updated it through imagined translation. The two hypotheses were examined in this study. In Experiment 1, forty participants (20 men) learned a regular 8-object layout and then walked straight forward to the testing position in the novel environment. Half remained in their orientation (0° condition) while the others turned to face the direction opposite to learning perspective (180° condition). In Experiment 2, after learning the layout, twenty participants (10 men) were disoriented before standing at the testing position in the novel environment, facing 180° opposite to the learning direction. Next, in both experiments, all participants were instructed to imagine themselves standing at the learning position and facing the learning direction (e.g., “Please imagine you are in the learning environment, standing at the learning position and facing the ball”). Then, participants turned 90° to the left or right before they performed spatial judgments from a perspective aligned with the learning direction (memory aligned), aligned with their facing direction (sensorimotor aligned), and a novel direction misaligned with the two directions mentioned above (misaligned). In each imagined perspective, participants pointed to all of the 8 objects of the layout (e.g., “Imagine you are facing the ball, please point to the candle”). Each participant performed 48 trials (8 target objects×3 imagined perspectives×2 blocks). The dependent measures were the latency and the absolute angular error of the pointing response. In Experiment 1, the pointing latency and absolute pointing error were subjected to mixed-model analyses of variance (ANOVAs), with imagined heading (memory aligned, sensorimotor aligned, misaligned) as the within-subject variable, imagined-real environment discrepancy (0°, 180°) as the between-subjects variable. In the 0° condition, participants pointed more accurately and faster from the memory aligned perspective than from the misaligned perspective (a memory alignment effect), and faster from the sensorimotor aligned perspective than from the misaligned perspective (a sensorimotor alignment effect). However, in the 180° condition, neither a memory alignment effect nor a sensorimotor alignment effect appeared. In Experiment 2, the pointing latency and absolute pointing error were subjected to one-way ANOVA, with the imagined perspective (memory aligned, sensorimotor aligned, misaligned) as the within-subject variable. Different from the participants in the 180° condition of Experiment 1, participants in Experiments 2 showed both a memory alignment effect and a sensorimotor alignment effect on pointing latency and absolute pointing error. In conclusion, results in the present study indicate that people can update an imagined environment by two means. They can update the imagined environment either by translation of the online representation or by retrieving the offline spatial memory and linking it to the online updating system.

Key words: spatial updating, spatial imagining, dual system processing, alignment effect, disorientation