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Letter recognition reveals pathways of second-order and third-order motion

Ho, Ching Elizabeth (1998) Letter recognition reveals pathways of second-order and third-order motion. Proceedings of the National Academy of Sciences of the United States of America, 95 (1). pp. 400-404. ISSN 0027-8424. PMCID PMC18237. doi:10.1073/pnas.95.1.400.

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How are second-order (texture-defined) and third-order (pattern-tracking) motions processed in our brains? As shown here in the context of an ambiguous motion task involving a nominal second-order stimuli first devised by Werkhoven et al., [Werkhoven, P., Sperling, G. & Chubb, C. (1993) Vision Res. 33, 463–485.], the observers fell into two distinct groups based on the direction of perceived motion. The differences were interpreted in terms of the algorithms used to extract motion: one group by using a second-order motion process and the other by using a third-order motion process. This was investigated further using a dual-task paradigm in which the interference between two tasks indicated the nature of processing involved. Observers who used third-order motion processing experienced interference with letter recognition and a more severe interference in dual third-order motion tasks. Observers who used second-order motion processing experienced interference with another second-order motion detection but not with letter recognition. Insofar as task interference implies the need for attention, the complex interference effects and the apparently paradoxical interference effects of second-order motion perception imply that there are multiple forms of attention. Whether two tasks interfere depends on whether they require the same form of attention. Insofar as spatio-temporal processing is assumed to be carried out in the dorsal stream and pattern recognition in the ventral stream, the interference patterns suggest that second-order motion may be computed entirely in the dorsal stream, and third-order motion may involve two computational processes, one of which shares computational resources with the letter recognition task in the ventral stream.

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Additional Information:© 1998 The National Academy of Sciences. Received May 28, 1997; accepted October 23, 1997. This paper owes much to the inspiration and invaluable guidance of Prof. G. Sperling, who has been a great coach and mentor. I also gratefully acknowledge Profs. C. Koch, F. Crick, J. Allman, K. Lau, J. Braun, and S. Shimojo for their constructive comments and support. This research was funded by the Lawrence Hansen Foundation and the Caltech Engineering Research Center and was conducted in Prof. C. Koch’s laboratory.
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Lawrence Hansen FoundationUNSPECIFIED
Caltech Engineering Research CenterUNSPECIFIED
Issue or Number:1
PubMed Central ID:PMC18237
Record Number:CaltechAUTHORS:20141202-111659749
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Official Citation:Ho, C. E. (1998). Letter recognition reveals pathways of second-order and third-order motion. Proceedings of the National Academy of Sciences, 95(1), 400-404.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52267
Deposited By: Jason Perez
Deposited On:03 Dec 2014 20:32
Last Modified:10 Nov 2021 19:23

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