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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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 Creators:
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
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: DOI: 10.3233/VES-2010-0374
BibTex Citekey: 6508
 Degree: -

Event

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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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Publ. Info: -
Pages: - Volume / Issue: 20 (3-4) Sequence Number: PA-21 Start / End Page: 282 Identifier: -