Grasping with the eyes: The role of elongation in visual recognition of manipulable objects
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Processing within the dorsal visual stream subserves object-directed action, whereas visual object recognition is mediated by the ventral visual stream. Recent findings suggest that the computations performed by the dorsal stream can nevertheless influence object recognition. Little is known, however, about the type of dorsal stream information that is available to assist in object recognition. Here, we present a series of experiments that explored different psychophysical manipulations known to bias the processing of a stimulus toward the dorsal visual stream in order to isolate its contribution to object recognition. We show that elongated-shaped stimuli, regardless of their semantic category and familiarity, when processed by the dorsal stream, elicit visuomotor grasp-related information that affects how we categorize manipulable objects. Elongated stimuli may reduce ambiguity during grasp preparation by providing a coarse cue to hand shaping and orientation that is sufficient to support action planning. We propose that this dorsal-stream-based analysis of elongation along a principal axis is the basis for how the dorsal visual object processing stream can affect categorization of manipulable objects.
KeywordsDorsal stream Tools Object recognition Object elongation
We thank M. Clara Barata and Thomas McKeeff for their comments on earlier versions of the manuscript and Matthew Finkbeiner and Jason Friedman for their help with the analysis of reach trajectories. J.A. was supported by funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement PCOFUND-GA-2009-246542 and from the Foundation for Science and Technology of Portugal. J.A., A.D., and J.F.M. were sponsored by a Foundation for Science and Technology of Portugal Project Grant PTDC/PSI-PCO/114822/2009. A.C. was supported by National Institute on Deafness and Other Communication Disorders Grant R01 DC006842 and by the Fondazione Cassa di Risparmio di Trento e Rovereto. B.Z.M. was supported in part by R21 NS076176 from NINDS. This research was supported by Foundation for Science and Technology of Portugal Project Grant PTDC/PSI-PCO/114822/2009.
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