Does an Oblique/Slanted Perspective during Virtual Navigation Engage Both Egocentric and Allocentric Brain Strategies?

Julien Barra,Denis Lebihan,Jean-Baptiste Poline,Alain Berthoz,Laetitia Laou,Frank Krueger

doi:10.1371/journal.pone.0049537

Abstract

Perspective (route or survey) during the encoding of spatial information can influence recall and navigation performance. In our experiment we investigated a third type of perspective, which is a slanted view. This slanted perspective is a compromise between route and survey perspectives, offering both information about landmarks as in route perspective and geometric information as in survey perspective. We hypothesized that the use of slanted perspective would allow the brain to use either egocentric or allocentric strategies during storage and recall. Twenty-six subjects were scanned (3-Tesla fMRI) during the encoding of a path (40-s navigation movie within a virtual city). They were given the task of encoding a segment of travel in the virtual city and of subsequent shortcut-finding for each perspective: route, slanted and survey. The analysis of the behavioral data revealed that perspective influenced response accuracy, with significantly more correct responses for slanted and survey perspectives than for route perspective. Comparisons of brain activation with route, slanted, and survey perspectives suggested that slanted and survey perspectives share common brain activity in the left lingual and fusiform gyri and lead to very similar behavioral performance. Slanted perspective was also associated with similar activation to route perspective during encoding in the right middle occipital gyrus. Furthermore, slanted perspective induced intermediate patterns of activation (in between route and survey) in some brain areas, such as the right lingual and fusiform gyri. Our results suggest that the slanted perspective may be considered as a hybrid perspective. This result offers the first empirical support for the choice to present the slanted perspective in many navigational aids.

Highlights

When we arrive in an unknown city, we can learn to navigate either by storing information on the sequence of streets that we take and the corresponding landmarks or episodes (‘‘egocentric’’ or ‘‘kinaesthetic’’ route strategy), or we can obtain a map of the city and plan and store our travel on a map-like ‘‘survey’’ view of the city (‘‘allocentric’’ strategy) [1,2]
We investigated the brain areas activated during the learning of a virtual city from a slanted perspective view, a topic that to our knowledge has never previously been studied
These results suggest that route and slanted perspectives may lead to similar brain activations, different from those that occur in survey perspective

Summary

Introduction

When we arrive in an unknown city, we can learn to navigate either by storing information on the sequence of streets that we take and the corresponding landmarks or episodes (‘‘egocentric’’ or ‘‘kinaesthetic’’ route strategy), or we can obtain a map of the city and plan and store our travel on a map-like ‘‘survey’’ view of the city (‘‘allocentric’’ strategy) [1,2]. Survey (allocentric) knowledge is characterized by an external perspective, such as an aerial or map-like view, allowing direct access to the global spatial layout. These two strategies develop during childhood [3,4]. We can combine these two strategies, which improves our ability to find new routes and shortcuts, and many recent studies have been devoted to their neural basis [5,6,7,8,9] Most studies in this domain have been performed using virtual reality, but new experiments using real locomotion have shown that it is possible to dissociate these strategies using behavioural paradigms [10]

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