Non-sensory inputs to angular path integration

Abstract

Non-sensory (cognitive) inputs can play a powerful role in monitoring one’s self-motion. Previously, we showed that access to spatial memory dramatically increases response precision in an angular self-motion updating task [1]. Here, we examined whether spatial memory also enhances a particular type of self-motion updating – angular path integration. “Angular path integration” refers to the ability to maintain an estimate of self-location after a rotational displacement by integrating internally-generated (idiothetic) self-motion signals over time. It was hypothesized that remembered spatial frameworks derived from vision and spatial language should facilitate angular path integration by decreasing the uncertainty of self-location estimates. To test this we implemented a whole-body rotation paradigm with passive, non-visual body rotations (ranging 40°–140°) administered about the yaw axis. Prior to the rotations, visual previews (Experiment 1) and verbal descriptions (Experiment 2) of the surrounding environment were given to participants. Perceived angular displacement was assessed by open-loop pointing to the origin (0°). We found that within-subject response precision significantly increased when participants were provided a spatial context prior to whole-body rotations. The present study goes beyond our previous findings by first establishing that memory of the environment enhances the processing of idiothetic self-motion signals. Moreover, we show that knowledge of one’s immediate environment, whether gained from direct visual perception or from indirect experience (i.e., spatial language), facilitates the integration of incoming self-motion signals.

The role of spatial memory and frames of reference in the precision of angular path integration

“…Previous work has found that non-sensory inputs, namely spatial memory, can play a powerful role in angular path integration (Arthur et al, 2007, 2009). Here we investigated the conditions under which spatial memory facilitates angular path integration.…”

“…Although these “low-level” cues play an important role in determining the magnitude of head and body rotations, “higherlevel” (non-sensory) inputs are significant factors as well. Previous work in our laboratory has demonstrated that spatial memory dramatically enhances angular path integration, which is manifested as increased within-subject response precision in tasks requiring participants to indicate their current position or orientation (Arthur, Philbeck, & Chichka, 2007, 2009). In these studies, we hypothesized that remembering an environment while navigating without vision yields a more precise self-location estimate.…”

“…Any uncertainty in the position / orientation estimate will be reflected in the variance of the distribution of behavioral responses. To test these predictions, in our past work (Arthur et al, 2007; 2009), we administered passive, whole-body stimulus rotations about an earth-vertical axis in darkness and asked participants to manipulate a pointer to indicate the magnitude of the rotations. In one block of trials, participants were either provided full vision or a verbal description of the laboratory prior to each non-visual rotation (“Preview” condition).…”

“…In another block, participants were not allowed vision prior to each rotation for the entire block of trials (“No-Preview” condition). Results showed that memory of the environment, whether constructed from visual previews or spatial language, facilitates angular path integration by enhancing the processing of idiothetic self-motion signals (Arthur et al, 2007, 2009). Interestingly, our findings suggest that this increased certainty plays a relatively small role in decreasing systematic errors in self-motion updating.…”

“…A strong prediction is that exocentric-referenced responses should show enhanced response precision when previews of the environment are provided prior to the path integration task, while egocentric-referenced responses should not show a preview benefit. In Experiment 1, we tested this prediction by comparing the exocentric-referenced manual pointing response used in our past work (Arthur et al, 2007, 2009) against egocentric-referenced verbal estimates of rotation magnitude (in which there was no requirement to respond relative to a location in the environment). In Experiment 2, we compared egocentric-referenced verbal estimates against an egocentric -referenced version of the manual pointing task.…”