English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  Grasp effects of visual illusions: Simply artifacts?

Franz, V., Bülthoff, H., & Fahle, M. (2002). Grasp effects of visual illusions: Simply artifacts?. Poster presented at 5. Tübinger Wahrnehmungskonferenz (TWK 2002), Tübingen, Germany.

Item is

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Franz, VH1, 2, Author              
Bülthoff, HH1, 2, Author              
Fahle, M, Author              
Affiliations:
1Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497794              
2Department Human Perception, Cognition and Action, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497797              

Content

show
hide
Free keywords: -
 Abstract: It is an open question whether visual illusions affect motor responses to the same extent as perceptual responses. In previous studies (e.g.: Franz, Gegenfurtner, Bülthoff, Fahle 2000) we found similar effects of the Ebbinghaus illusion on perception and on grasping. This finding contradicts a strong version of the action versus perception hypothesis (Milner Goodale, 1995) which states that the motor system is unaffected by visual illusions. Here, we tested whether our grasp effects might have been artifacts. This could be the case if the motor system treated the illusion inducing context elements as obstacles and tried to avoid them. To test for this possibility, we varied the distance between context elements and target. An aluminum disc (31, 34, or 37 mm in diameter, 5 mm in height) was positioned as target on a board. Around the target either small or large context discs (10 or 58 mm in diameter) were drawn at near or far distances (24 or 31 mm midpoint to nearest point on context circles). Close to the board a monitor was mounted on which a comparison disc was displayed. In the perceptual task 52 subjects adjusted the size of the comparison stimulus to match the size of the target. In the grasping task subjects grasped the target. Subjects wore shutter glasses and could not see their hand during grasping. The grasp trajectory was recorded and the maximum preshape aperture was calculated. The motor illusion responded to the variation of distance between context elements and target in exactly the same way as the perceptual illusion. None of three different obstacle avoidance hypotheses can explain these results. Our results suggest that the same signals are responsible for the perceptual and for the motor illusion. This either indicates that the action versus hypothesis needs modification, or that the Ebbinghaus illusion is generated before the separation of the perceptual and the motor streams.

Details

show
hide
Language(s):
 Dates: 2002-02
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: BibTex Citekey: 1613
 Degree: -

Event

show
hide
Title: 5. Tübinger Wahrnehmungskonferenz (TWK 2002)
Place of Event: Tübingen, Germany
Start-/End Date: 2002-02-22 - 2002-02-24

Legal Case

show

Project information

show

Source 1

show
hide
Title: TWK 2002: Beiträge zur 5. Tübinger Wahrnehmungskonferenz
Source Genre: Proceedings
 Creator(s):
Bülthoff, HH1, Editor            
Gegenfurtner, KR, Editor            
Mallot, HA, Editor            
Ulrich, R, Editor
Affiliations:
1 Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497794            
Publ. Info: Kirchentellinsfurt, Germany : Knirsch
Pages: - Volume / Issue: - Sequence Number: - Start / End Page: 138 Identifier: ISBN: 3-927091-56-1