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Published online on December 18, 2007, 10.1073/pnas.0709664104
PNAS | December 26, 2007 | vol. 104 | no. 52 | 21014-21019


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BIOLOGICAL SCIENCES / PSYCHOLOGY
Global topological dominance in the left hemisphere

Bo Wang*, Tian Gang Zhou, Yan Zhuo*, and Lin Chen

State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101 Beijing, China

Communicated by Robert Desimone, Massachusetts Institute of Technology, Cambridge, MA, October 17, 2007 (received for review August 9, 2007)

A series of experiments with right-handers demonstrated that the left hemisphere (LH) is reliably and consistently superior to the right hemisphere (RH) for global topological perception. These experiments generalized the topological account of lateralization to different kinds of topological properties (including holes, inside/outside relation, and "presence vs. absence") in comparison with a broad spectrum of geometric properties, including orientation, distance, size, mirror-symmetry, parallelism, collinearity, etc. The stimuli and paradigms used were also designed to prevent subjects from using various nontopological properties in performing the tasks of topological discrimination. Furthermore, task factors commonly considered in the study of hemispheric asymmetry, such as response latency vs. accuracy, vertical vs. horizontal presentation, detection vs. recognition, and simultaneous vs. sequential judgment, were manipulated to not be confounding factors. Moreover, left-handed subjects were tested and showed the right lateralization of topological perception, in the opposite direction of lateralization compared with right-handers. In addition, the functional magnetic resonance imaging measure revealed that only a region in the left temporal gyrus was consistently more activated across subjects in the task of topological discrimination, consistent with the behavioral results. In summary, the global topological dominance in the LH is well supported by the converging evidence from the variety of paradigms and techniques, and it suggests a unified solution to the current major controversies on visual lateralization.

visual lateralization | perception | temporal gyrus | holes | inside/outside relation

Author contributions: B.W., Y.Z., and L.C. designed research; B.W. performed research; T.G.Z. and Y.Z. contributed new reagents/analytic tools; B.W., T.G.Z., and Y.Z. analyzed data; and B.W., Y.Z., and L.C. wrote the paper.

The authors declare no conflict of interest.

This article contains supporting information online at www.pnas.org/cgi/content/full/0709664104/DC1.

*To whom correspondence may be addressed. E-mail: bwang{at}cogsci.ibp.ac.cn or yzhuo{at}cogsci.ibp.ac.cn

© 2007 by The National Academy of Sciences of the USA


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PNAS 2007 104: 20637-20638. [Full Text]  

Holes, objects, and the left hemisphere
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PNAS 2008 105: 1103-1104. [Extract] [Full Text]  



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S. He
Holes, objects, and the left hemisphere
PNAS, January 29, 2008; 105(4): 1103 - 1104.
[Full Text] [PDF]