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Modeling Learned Categorical Perception in Human Vision.

Casey, MC and Sowden, PT (2012) Modeling Learned Categorical Perception in Human Vision. Neural Networks, 33. pp. 114-126.

Casey&Sowden Neural Networks 2012 prepub.pdf
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A long standing debate in cognitive neuroscience has been the extent to which perceptual processing is influenced by prior knowledge and experience with a task. A converging body of evidence now supports the view that task does influence perceptual processing, leaving us with the challenge of understanding the locus of, and mechanisms underpinning, these influences. An exemplar of this influence is learned categorical perception (CP), in which there is superior perceptual discrimination of stimuli that are placed in different categories. Psychophysical experiments on humans have attempted to determine whether early cortical stages of visual analysis change as a result of learning a categorization task. However, while some results indicate that changes in visual analysis occur, the extent to which earlier stages of processing are changed is still unclear. To explore this issue, we develop a biologically motivated neural model of hierarchical vision processes consisting of a number of interconnected modules representing key stages of visual analysis, with each module learning to exhibit desired local properties through competition. With this system level model, we evaluate whether a CP effect can be generated with task influence to only the later stages of visual analysis. Our model demonstrates that task learning in just the later stages is sufficient for the model to exhibit the CP effect, demonstrating the existence of a mechanism that requires only a high-level of task influence. However, the effect generalizes more widely than is found with human participants, suggesting that changes to earlier stages of analysis may also be involved in the human CP effect, even if these are not fundamental to the development of CP. The model prompts a hybrid account of task-based influences on perception that involves both modifications to the use of the outputs from early perceptual analysis along with the possibility of changes to the nature of that early analysis itself.

Item Type: Article
Divisions : Faculty of Health and Medical Sciences > School of Psychology
Authors :
Date : September 2012
Identification Number : 10.1016/j.neunet.2012.05.001
Uncontrolled Keywords : Categorical perception, Modular neural networks, Hebbian learning, Task influence
Related URLs :
Additional Information : NOTICE: this is the author’s version of a work that was accepted for publication in <Neural Networks>. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Neural Networks, 33: 11-126. September 2012.
Depositing User : Symplectic Elements
Date Deposited : 22 Jan 2013 16:31
Last Modified : 23 Sep 2013 19:25

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