| Positive correlation in the bisection of long and short horizontal Oppel-Kundt illusory gradients: Implications for the interpretation of the "cross-over" effect in spatial neglect. | |
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MedLine Citation:
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PMID: 20926070 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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Right brain damaged patients with left spatial neglect typically bisect long horizontal lines to the right of their midpoint. However, bisections of very short lines can favour the emergence of a paradoxical "cross-over" effect in which lines are bisected to the left of the true midpoint. It has been suggested that in healthy participants similar variations in the position of the subjective line midpoint can be observed in the bisections of long and short Oppel-Kundt (O-K) illusory gradients (Savazzi et al., 2007). This analogy was taken as proof that patients with neglect suffer a distorted representation of horizontal space that is equivalent to illusory distortions that O-K gradients induce in the intact brain (Savazzi et al., 2007). In contrast to this proposal, however, it has been noted that reversal of O-K illusion with short gradients was never described in literature (Doricchi et al., 2008). To resolve this incongruence, it was argued that such a reversal can be observed in healthy participants showing strong conventional illusory effects with long gradients (Savazzi, 2008). This proposal suggests that the greater the shift in the conventional direction of the illusion for long gradients, the greater the shift in the opposite direction with equivalent short gradients (i.e., negative correlation). Here we tested this hypothesis in a sample of 100 healthy participants who bisected horizontal O-K illusory gradients of different lengths (2, 4, 8 and 16cm). We found no reversal of O-K illusion with short gradients and a positive, rather than negative, correlation between bisection of long and short gradients. Participants showing strong illusory effects in the bisection of long gradients showed analogous effects in the bisection of very short ones. These findings do not support the space anisometry interpretation of line bisection performance and the cross-over effect in patients with neglect. |
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Authors:
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Nicola Binetti; Marilena Aiello; Sheila Merola; Michela Bruschini; Francesca Lecce; Enrica Macci; Fabrizio Doricchi |
Publication Detail:
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Type: Journal Article Date: 2010-09-09 |
Journal Detail:
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Title: Cortex; a journal devoted to the study of the nervous system and behavior Volume: 47 ISSN: 1973-8102 ISO Abbreviation: Cortex Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-03-22 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0100725 Medline TA: Cortex Country: Italy |
Other Details:
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Languages: eng Pagination: 608-16 Citation Subset: IM |
Copyright Information:
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Copyright © 2010 Elsevier Srl. All rights reserved. |
Affiliation:
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Fondazione Santa Lucia IRCCS, Rome, Italy; Dipartimento di Psicologia, Università degli Studi di Roma "La Sapienza", Italy. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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