Academic journal article Memory & Cognition

Getting Completely Turned Around: How Disorientation Impacts Subjective Straight Ahead

Academic journal article Memory & Cognition

Getting Completely Turned Around: How Disorientation Impacts Subjective Straight Ahead

Article excerpt

Published online: 14 August 2014

© Psychonomic Society, Inc. 2014

Abstract In manipulating a pointer to indicate subjective straight ahead (SSA), participants were more variable after a series of whole-body rotations in conjunction with external sensory blockade than after external sensory blockade alone. The variability of reported SSA did not increase consequent to a temporal delay matched to the time taken by the rotation procedure. These results suggest that an observer's egocentric reference frame is more complex and less stable than has previously been thought.

Keywords Memory . Spatial cognition

Keeping track of heading and position with respect to surrounding objects is a crucial ability for humans (and indeed for many other organisms) as they move about an environment. In seeking to understand how an observer uses knowledge about object locations when tracking heading and position, theorists have drawn a distinction between egocentric and allocentric reference frames. In an egocentric reference frame, object locations are encoded relative to a reference system aligned on the observer. In an allocentric reference frame, object locations are encoded relative to a reference frame defined by features of the environment rather than by the observer (Klatzky, 1998).

Heading and position are tracked on the basis of information from external and internal sensory systems. Vision and audition are the most important of the external systems. Internal- idiothetic-sensory information can come from the vestibular, proprioceptive, or kinesthetic systems (Philbeck & Sargent, 2013). When external sensory input is minimal, heading and position must be tracked on the basis of primarily idiothetic information. This would be the case, for example, if one were walking through a forest in darkness. As would be expected, heading and position tend to be tracked less successfully under such conditions. In short, one tends to become disoriented with respect to the environment. Disorientation can have devastating consequences-as, for example, in aviation, hiking, or even navigation in once-familiar settings for patients with memory disorders. Thus, there is a pressing need to understand the process of tracking heading and position under minimal external sensory input.

Failures in the tracking of heading under minimal external sensory input have been studied with a blind-pointing task in which participants learn the locations of a set of objects and then attempt to point to the objects from a central location, in the absence of visual and auditory input (Wang & Spelke, 2000). Of particular interest is the effect on performance of an orientation challenge comprising one or more full-body rotations. One can assess the effects of such a challenge by computing a signed angular error score for each response of each participant to each object in the set. For a given participant and object, the individual error and pointing error are, respectively, the mean and standard deviation of the error scores across responses. For a given participant, the heading error and configuration error are, respectively, the mean and standard deviation of the individual errors across objects. In response to increasing degrees of orientation challenge, the heading error for a group of participants tends to be distributed with increasing uniformity over the 360-deg range, implying that participants tend to become increasingly disoriented with respect to the objects in the set.1 The average pointing errors across participants and objects tend to increase, implying that participants' knowledge of the locations of the objects tends to become less precise. Finally, the average configuration errors across participants tend to increase, implying that participants' knowledge of the between-object location relationships tends also to become less precise (Holmes & Sholl, 2005; Mou, McNamara, Rump, & Xiao, 2006; Sargent, Dopkins, Philbeck, & Arthur, 2008; Waller & Hodgson, 2006; Wang, 2012; Wang & Spelke, 2000; Xiao, Mou, & McNamara, 2009). …

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