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  Path integration in the third dimension

Barnett-Cowan, M., Meilinger, T., Vidal, M., & Bülthoff, H. (2010). Path integration in the third dimension. Poster presented at XXVI Bárány Society Meeting, Reykjavik, Iceland.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0013-BEE4-3 Version Permalink: http://hdl.handle.net/21.11116/0000-0002-9DDB-7
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Barnett-Cowan, M1, 2, Author              
Meilinger, T1, 2, Author              
Vidal, M, Author              
Bülthoff, HH1, 2, Author              
Affiliations:
1Department Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497797              
2Max Planck Institute for Biological Cybernetics, Max Planck Society, Spemannstrasse 38, 72076 Tübingen, DE, ou_1497794              

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 Abstract: Path integration, the ability to update the position and orientation of external locations predominantly on the basis of internal cues, is an effective strategy for spatial navigation. While extensive work has been done on evaluating path integration in the horizontal plane, little is known for movements in the vertical (third) dimension. Here we assess whether pointing to the origin of translational movement in vertical planes is similar to that found for movement in the horizontal plane alone. 15 observers sat upright in a racecar seat that was mounted to the flange of a modified KUKA c anthropomorphic robot arm (Fig. 1a). An LCD display was 50cm in front of the observers who were otherwise tested in the dark. Sensory information was manipulated by providing visual (optic flow, limited lifetime star field), vestibular-kinesthetic (passive self motion with eyes closed), or visual and vestibularkinesthetic motion cues. Movement trajectories consisted of two segment lengths (1st: 0.4 m, 2 nd: 1 m; ± 0.24 m/s2 peak acceleration). Movements in the horizontal, sagittal and frontal planes consisted of: forward-rightward (FR) or rightward-forward (RF), downward-forward (DF) or forward-downward (FD), and downward-rightward (DR) or rightward-downward (RD) movements respectively. The angle of the two segments was either 45◦ or 90◦. A 15 s pause preceded each trajectory. Observers pointed back to their origin by moving an arrow that was superimposed on an avatar presented on the screen (Fig. 1b). Movement of the arrow was constrained to the trajectory’s plane and controlled by a joystick. The avatarwas presented from frontal, sagittal and horizontal viewpoints. Observers were allowed to use any or all viewpoints to answer. The starting orientation of the arrow was randomized across trials. Each condition was repeated 3 times and presented in random order. Signed error and response time were analyzed as dependent variables. Observers were more likely to underestimate angle size (average data less than 0◦; Fig. 1c) for movement in the horizontal plane compared to the vertical planes. In the frontal plane observers were more likely on average to overestimate angle size (average data more than 0◦), while there was no such bias in the sagittal plane. Another discrepancy between horizontal and vertical planes was that responses in the vertical planes were more closely related to a response bias suggesting that the path segments were of equal length (solid grey line). Finally, observers responded slower (Fig. 1d) when answering based on vestibular-kinesthetic information alone. These results suggest that human path integration based on vestibular-kinesthetic information alone takes longer than when visual information is present. Path integration has been well established as a means used to resolve where an observer originated but is prone to underestimates of the angle one has moved through. Our results show this for translational movement but only within the horizontal plane. In the vertical planes pointing may have been directed in accordance with an assumption of equal path lengths. This result suggests that alternative strategies for determining one’s origin may be adopted when moving in the third dimension which may relate to the fact that humans experience movement mostly within the horizontal plane.

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 Dates: 2010-08
 Publication Status: Published in print
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 Identifiers: DOI: 10.3233/VES-2010-0374
BibTex Citekey: 6508
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Title: XXVI Bárány Society Meeting
Place of Event: Reykjavik, Iceland
Start-/End Date: 2010-08-18 - 2010-08-21

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Title: Journal of Vestibular Research
Source Genre: Journal
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Pages: - Volume / Issue: 20 (3-4) Sequence Number: PA-21 Start / End Page: 282 Identifier: -