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W. Todd Maddox
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Email: maddox@psy.utexas.edu
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Dr. Maddox received his Ph.D. from the University of California, Santa Barbara. His research interests are in the area of visual perception, cognition, and mathematical modeling.
I have broad interests within the general area of perception/cognition. The long-term objective of my research is to better understand the complex interplay between perception and cognition and to understand the connection between these processes and the neurophysiology of the brain. The approach is to develop and test formal models of perceptual and cognitive processes. Corey Bohil and I have developed and are currently testing a series of multidimensional signal detection models of probabilistic categorization. In particular, we are interested in examining observer's sensitivity to base-rate and payoff manipulations. Our approach has been to develop an "optimal" model of categorization performance (i.e., a model that generates responses that maximize long-run performance), and then to incorporate various "suboptimalities" in an attempt to isolate the types of suboptimalities inherent in human categorization performance. Sergei Bogdanov and I are examining models of perceptual representation and are attempting to isolate the effects of representation on performance in higher level cognitive tasks. One factor that we are particularly interested in is the effect of selective attention on perceptual representation and performance. Dr. Vincent Filoteo (a cognitive neuropsychologist at the University of Utah) and I have been applying some of these models of normal perception and cognition to perceptual and cognitive processing in normal aging, and in brain damaged individuals. In particular, we have investigated attentional processes in patients with Parkinson's disease and in normal aging. Currently, we are collecting categorization data from several patient populations (e.g., Huntington's disease, Parkinson's disease, amnesiacs) in an attempt to link categorization processes to particular brain regions. Finally, in collaboration with Dr. William K. Estes at Harvard University, we are developing and testing basic connections and exemplar-similarity models of recognition memory. Currently we are investigating the locus of the "mirror" effect in recognition memory.
Maddox, W. T., & Filoteo, J. V. (under review). Effects of stimulus integrality on visual attention in older and younger adults: A quantitative model-based analysis. Psychology and Aging.
Maddox, W. T. , & Bohil, C. J. (under review). Base-rate and payoff effects in multidimensional perceptual categorization. Journal of Experimental Psychology: Learning, Memory, & Cognition.
Maddox, W. T., Ashby, F. G., & Gottlob, L. X. (1998). Response time distributions in multidimensional perceptual categorization, Perception & Psychophysics, in press.
Maddox, W. T., & Ashby, F. G. (1998). Attention and the formation of linear decision bounds: Commentary on McKinley and Nosofsky (1996). Journal of Experimental Psychology: Human Perception and Performance, in press.
Maddox, W. T., & Estes, W. K. (1997). Direct and indirect stimulus-frequency effects in recognition. Journal of Experimental Psychology: Learning, Memory, and Cognition, 23, 539-559.
Maddox, W. T., Filoteo, J. V., Delis, D. C., & Salmon, D. P. (1996). Visual selective attention deficits in patients with Parkinson's disease: A quantitative model-based approach. Neuropsychology, 10, 197-218.
Maddox, W. T., & Ashby, F. G. (1996). Perceptual separability, decisional separability, and the identification-speeded classification relationship. Journal of Experimental Psychology: Human Perception and Performance, 22, 795-817.
Maddox, W. T. (1995). Baserate effects in multidimensional perceptual categorization. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 1-14.
