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 present study examined how cold pressor stimulation influences electrophysiological correlates of arousal. We measured the P50 auditory evoked response potential in two groups of subjects who immersed their foot in either cold (0–2°C) or room temperature (22–24°C) water for 50 seconds. The P50, which was recorded before and after stimulation, is sleep-state dependent and sensitive to states of arousal in clinical populations. We found a significant reduction in P50 amplitude after exposure to cold, but not room temperature water. In comparison with other studies, these results indicate that cold pressor stimulation in normal subjects may evoke a regulatory process that modulates the P50 amplitude, perhaps to preserve the integrity of sensory perception, even as autonomic and subjective aspects of arousal increase.

Blind walking has become a common measure of perceived target location. This article addresses the possibility that blind walking might vary systematically within an experimental session as participants accrue exposure to nonvisual locomotion. Such variations could complicate the interpretation of blind walking as a measure of perceived location. We measured walked distance, velocity, and pace length in indoor and outdoor environments (1.5–16.0 m target distances). Walked distance increased over 37 trials by approximately 9.33% of the target distance; velocity (and to a lesser extent, pace length) also increased, primarily in the first few trials. In addition, participants exhibited more unintentional forward drift in a blindfolded marching-in-place task after exposure to nonvisual walking. The results suggest that participants not only gain confidence as blind-walking exposure increases, but also adapt to nonvisual walking in a way that biases responses toward progressively longer walked distances.

D. R. Proffitt and colleagues (e. g., D. R. Proffitt, J. Stefanucci, T. Banton, & W. Epstein, 2003) have suggested that objects appear farther away if more effort is required to act upon them (e.g., by having to throw a ball). The authors attempted to replicate several findings supporting this view but found no effort-related effects in a variety of conditions differing in environment, type of effort, and intention to act. Although they did find an effect of effort on verbal reports when participants were instructed to take into account nonvisual (cognitive) factors, no effort-related effect was found under apparent- and objective-distance instruction types. The authors’ interpretation is that in the paradigms tested, effort manipulations are prone to influencing response calibration because they encourage participants to take nonperceptual connotations of distance into account while leaving perceived distance itself unaffected. This in no way rules out the possibility that effort influences perception in other contexts, but it does focus attention on the role of response calibration in any verbal distance estimation task.

Blindwalking has become a common measure of perceived absolute distance and location, but it requires a relatively large testing space and cannot be used with people for whom walking is difficult or impossible. In the present article, we describe an alternative response type that is closely matched to blindwalking in several important respects but is less resource intensive. In the blindpulling technique, participants view a target, then close their eyes and pull a length of tape or rope between the hands to indicate the remembered target distance. As with blindwalking, this response requires integration of cyclical, bilateral limb movements over time. Blindpulling and blindwalking responses are tightly linked across a range of viewing conditions, and blindpulling is accurate when prior exposure to visually guided pulling is provided. Thus, blindpulling shows promise as a measure of perceived distance that may be used in nonambulatory populations and when the space available for testing is limited.

Previous studies have demonstrated large errors (over 30°) in visually perceived exocentric directions (the direction between two objects that are both displaced from the observer’s location; e.g., Philbeck et al., in press). Here, we investigated whether a similar pattern occurs in auditory space. Blindfolded participants either attempted to aim a pointer at auditory targets (an exocentric task) or gave a verbal estimate of the egocentric target azimuth. Targets were located at 20° to 160° azimuth in the right hemispace. For comparison, we also collected pointing and verbal judgments for visual targets. We found that exocentric pointing responses exhibited sizeable undershooting errors, for both auditory and visual targets, that tended to become more strongly negative as azimuth increased (up to −19° for visual targets at 160°). Verbal estimates of the auditory and visual target azimuths, however, showed a dramatically different pattern, with relatively small overestimations of azimuths in the rear hemispace. At least some of the differences between verbal and pointing responses appear to be due to the frames of reference underlying the responses; when participants used the pointer to reproduce the egocentric target azimuth rather than the exocentric target direction relative to the pointer, the pattern of pointing errors more closely resembled that seen in verbal reports. These results show that there are similar distortions in perceiving exocentric directions in visual and auditory space.