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Jorge Almeida, Bradford Mahon, Ken Nakayama, Alfonso Caramazza; Categorical priming: using continuous flash suppression in an object categorization task. Journal of Vision 2008;8(6):840. doi: https://doi.org/10.1167/8.6.840.
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© ARVO (1962-2015); The Authors (2016-present)
Neural specificity in the ventral object processing stream for manipulable objects is thought to reflect visual object recognition, whereas specificity in the dorsal stream for manipulable objects is thought to reflect visuomotor processing required for manipulating and grasping objects. We investigated whether the outputs of the dorsal stream affect object categorization, using a combination of priming techniques. Previous research has demonstrated that pictures of tools presented under continuous flash suppression (CFS) do not activate ventral temporal regions, whereas they activate the same dorsal stream regions as do visible tools (Fang and He, 2005, NN, 10, 1380–1385). In contrast, stimuli presented under backward masking do activate ventral temporal regions (Dehaene et al., 2001. NN, 4(7), 752–758). In Experiments 1 and 2, animal and tool prime pictures were presented under CFS, and were immediately followed by visible images of animals and tools, and participants were required to indicate the category of the visible stimulus by means of a button response. D-prime measures confirmed the invisibility of the primes. In both these experiments we obtained a categorical priming effect restricted to the domain of tools - participants were faster to categorize target pictures of tools, but not animals, when presented with congruent primes compared to incongruent primes. This category-related priming effect is not due to differences in the two stimulus sets in terms of their general ability to lead to priming. In Experiment 3, backward masking paradigm was used over the same items as in Experiment 2, and a priming effect was obtained for both categories. We argue that the pattern of findings across the experiments is related to the reduction in neural activity in ventral temporal areas for stimuli presented under CFS. These data indicate that the outputs of dorsal stream processing are relevant to category-level judgments of subsequently presented tool stimuli.
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