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1.  The Role of Spatial Memory and Frames of Reference in the Precision of Angular Path Integration 
Acta psychologica  2012;141(1):112-121.
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. 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. We hypothesized that the benefit of spatial memory is particularly likely in spatial updating tasks in which one’s self-location estimate is referenced to external space. To test this idea, we administered passive, nonvisual body rotations (ranging 40° – 140°) about the yaw axis and asked participants to use verbal reports or open-loop manual pointing to indicate the magnitude of the rotation. Prior to some trials, previews of the surrounding environment were given. We found that when participants adopted an egocentric frame of reference, the previously-observed benefit of previews on within-subject response precision was not manifested, regardless of whether remembered spatial frameworks were derived from vision or spatial language. We conclude that the powerful effect of spatial memory is dependent on one’s frame of reference during self-motion updating.
doi:10.1016/j.actpsy.2012.07.003
PMCID: PMC3436123  PMID: 22885073
spatial memory; path integration; vestibular navigation; manual pointing; perception and action
2.  Non-sensory inputs to angular path integration 
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.
doi:10.3233/VES-2009-0354
PMCID: PMC2892260  PMID: 20448337
Spatial memory; path integration; vestibular navigation; manual pointing
3.  Progressive locomotor recalibration during blind walking 
Perception & psychophysics  2008;70(8):1459-1470.
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.
doi:10.3758/PP.70.8.1459
PMCID: PMC2892263  PMID: 19064490
4.  Exploring the Process of Progressive Disorientation 
Acta psychologica  2008;129(2):234-242.
While an increasing number of behavioral studies examining spatial cognition use experimental paradigms involving disorientation, the process by which one becomes disoriented is not well explored. The current study examined this process using a paradigm in which participants were blindfolded and underwent a succession of 70° or 200° passive, whole body rotations around a fixed vertical axis. After each rotation, participants used a pointer to indicate either their heading at the start of the most recent turn or their heading at the start of the current series of turns. Analyses showed that in both cases, mean pointing errors increased gradually over successive turns. In addition to the gradual loss of orientation indicated by this increase, analysis of the pointing errors also showed evidence of occasional, abrupt loss orientation. Results indicate multiple routes from an oriented to a disoriented state, and shed light on the process of becoming disoriented.
doi:10.1016/j.actpsy.2008.06.005
PMCID: PMC2575240  PMID: 18691681
spatial cognition; disorientation
5.  Misperception of exocentric directions in auditory space 
Acta psychologica  2008;129(1):72-82.
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.
doi:10.1016/j.actpsy.2008.04.008
PMCID: PMC2614239  PMID: 18555205
manual pointing; auditory space perception; perception / action; perceived direction; spatial cognition
6.  Large manual pointing errors, but accurate verbal reports, for indications of target azimuth 
Perception  2008;37(4):511-534.
Many tasks have been used to probe human directional knowledge, but relatively little is known about the comparative merits of different means of indicating target azimuth. Few studies have compared action-based versus non-action-based judgments for targets encircling the observer. This comparison promises to illuminate not only the perception of azimuths in the front and rear hemispaces, but also the frames of reference underlying various azimuth judgments, and ultimately their neural underpinnings. We compared a response in which participants aimed a pointer at a nearby target, with verbal azimuth estimates. Target locations were distributed between 20 and 340 deg. Non-visual pointing responses exhibited large constant errors (up to −32 deg) that tended to increase with target eccentricity. Pointing with eyes open also showed large errors (up to −21 deg). In striking contrast, verbal reports were highly accurate, with constant errors rarely exceeding +/− 5 deg. Under our testing conditions, these results are not likely to stem from differences in perception-based vs. action-based responses, but instead reflect the frames of reference underlying the pointing and verbal responses. When participants used the pointer to match the egocentric target azimuth rather than the exocentric target azimuth relative to the pointer, errors were reduced.
PMCID: PMC2702262  PMID: 18546661
open loop pointing; spatial cognition; perception/action; perceived direction

Results 1-6 (6)