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Two Hands, One Perception: How Bimanual Haptic Information Is Combined by the Brain.
MedLine Citation:
PMID:  22031771     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Introduction: Humans routinely use both of their hands to gather information about shape and texture of objects. Yet, the mechanisms of how the brain combines haptic information from the two hands to achieve a unified percept are unclear. This study systematically measured the haptic precision of humans exploring a virtual curved object contour with one or both hands to understand if the brain integrates haptic information from the two hemispheres. Bayesian perception theory predicts that redundant information from both hands should improve haptic estimates. Thus, exploring an object with two hands should yield haptic precision that is superior to unimanual exploration. Methods: A bimanual robotic manipulandum passively moved the hands of 20 blindfolded right-handed adult participants along virtual curved contours. Subjects indicated which contour was more "curved" (forced choice) between two stimuli of different curvature. Contours were explored uni- or bimanually at two orientations (towards or away from the body midline). Respective psychophysical discrimination thresholds were computed. Results: First, subjects showed a tendency for one hand being more sensitive than the other with most of the subjects exhibiting a hand bias. Second, bimanual thresholds were mostly within the range of the corresponding unimanual thresholds and were not predicted by a maximum-likelihood estimation model. Third, bimanual curvature perception tended to be biased towards the motorically dominant hand, not towards the haptically more sensitive left hand. Conclusion: Two-handed exploration does not necessarily improve haptic sensitivity. We found no evidence that haptic information from both hands is integrated using a maximum-likelihood estimation mechanism. Rather, results are indicative of a process of "sensory selection", where information from the dominant, right hand is used, although the left non-dominant hand may yield more precise haptic estimates.
Authors:
Valentina Squeri; Alessandra Sciutti; Monica Gori; Lorenzo Masia; Giulio Sandini; Juergen Konczak
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-10-26
Journal Detail:
Title:  Journal of neurophysiology     Volume:  -     ISSN:  1522-1598     ISO Abbreviation:  -     Publication Date:  2011 Oct 
Date Detail:
Created Date:  2011-10-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
1IIT Istituto Italiano di Tecnologia.
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