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  Size Discrimination of seen and grasped objects and the effect of presentation time

Ernst, M., van Veen, H.-J., & Bülthoff, H. (1998). Size Discrimination of seen and grasped objects and the effect of presentation time. Perception, 27(ECVP Abstract Supplement), 12-13.

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 Creators:
Ernst, MO1, 2, Author              
van Veen, H-J1, 2, 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: We investigated visuo - motor integration in grasping by studying haptic, visual, and cross-modal size discrimination. Our main interest concerned the effect of presentation time on discrimination performance and the differences between intramodal and cross-modal thresholds. The experiments were conducted in a virtual environment in which two force-feedback devices (PHANToMTM) provided haptic information to the thumb and the index finger. Stereoscopically rendered objects were used for the visual presentation. In a two-interval forced-choice paradigm subjects had to determine which interval contained the larger object (we used cubes in all cases). Depending on condition, subjects either saw or felt each cube for a specified time. Feeling a cube required subjects to perform a two-finger grasp. The intramodal tasks were repeated with an appropriate mask between the two presentations; in these runs haptic masking consisted of randomly disturbing the finger span by the force-feedback devices. Intramodal thresholds (+/-4 visual - visual; +/-7 haptic - haptic) were significantly smaller than cross-modal thresholds (+/-13 visual - haptic; +/-14 haptic - visual). Gradually decreasing the presentation time in the intramodal conditions to less than 50 ms increased the thresholds monotonically, but significantly less so for the visual - visual condition (from +/-4 to +/-6) than for the haptic - haptic condition (from +/-7 to +/-20). We found no significant effect of masking on these thresholds. Visuo - motor adaptation studies have shown that the coordinate transformation from vision to touch exhibits a considerable amount of plasticity. We hypothesise that the continuous recalibration of this transformation during the experiment constitutes the reason for the inflated cross-modal thresholds. Furthermore, we conclude that acquiring precise size information is much slower in the haptic modality than it is in vision.

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 Dates: 1998-08
 Publication Status: Published in print
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 Identifiers: BibTex Citekey: 1630
DOI: 10.1177/03010066980270S101
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Title: 21st European Conference on Visual Perception (ECVP 1998)
Place of Event: Oxford, UK
Start-/End Date: 1998-08-24 - 1998-08-28

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Title: Perception
Source Genre: Journal
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Publ. Info: London : Pion Ltd.
Pages: - Volume / Issue: 27 (ECVP Abstract Supplement) Sequence Number: - Start / End Page: 12 - 13 Identifier: ISSN: 0301-0066
CoNE: https://pure.mpg.de/cone/journals/resource/954925509369