Category Laboratory

Rules and Exemplars in Perceptual Categorization

This line of research has examined the role of rules and exemplars in perceptual categorization. Some of this work has examined the role of exemplars or the role of rules and other work has examined their interaction over the course of learning. One hypotheses we’ve investigated is that people may sometimes categorize by using explicit rules but eventually use similarity to stored exemplars. This earlier work informs our current work on perceptual expertise as well as our research on conceptual change. This work also spawned a series of papers contrasting single-system exemplar models with multiple system models that assume that categorization is subserved by a functionally independent system from other kinds of memory.

Much of this research has been funded by grants from the National Science Foundation, the National Institutes of Health, and the Vanderbilt Discovery Grant Program

The Development of Perceptual Expertise

One major component of our research asks how experts become experts. Do they perceive the world differently? Do they know more? Do they know different things? Do they use knowledge differently? Do they use certain knowledge more quickly? Or is there some combination of all of these? Our laboratory approaches these questions using behavioral experiments, cognitive neuroscience techniques, and computational modeling. We are working on a variety of projects examining the time-course of categorization in expert and novice domains, how categorization changes with expertise, and the nature of so-called “holistic” perception seen in experts. Much of this work builds on our work examining rule-based and exemplar-based categorization.

This research is funded by grants from the National Science Foundation and the James S. McDonnell Foundation.

Neural Basis of Perceptual Decision Making

In an ongoing collaboration with Gordon Logan and Jeffrey Schall, we are linking cognitive models of categorization, attention, and control with neurophysiological data. We have formulated various stochastic models of perceptual decisions and control over those decisions. These models are tested by fitting them to behavior of humans and macaque monkeys. The models are further evaluated by contrasting the accumulation of evidence in the models with the changing patterns of single unit neural activity recorded from awake behaving monkeys.

This research is funded by grants from the National Science Foundation and the National Institutes of Health. This collaborative project is also supported in part by a grant to Gordon Logan and Jeffrey Schall from AFOSR.

Understanding Conceptual and Cultural Change

This collaborative project with Norbert Ross in Anthropology and David Noelle in Computer Science at UC Merced explores cultural and expertise differences in conceptual and perceptual knowledge, conceptual and perceptual learning, and conceptual change in individuals, and explores the computational mechanisms that underlie conceptual knowledge. We bring together tools, techniques, and insights from cognitive psychology, anthropology, and computer science to investigate the dynamics of conceptual knowledge.

This research is funded by a grant from the National Science Foundation.

Synesthesia

This collaborative research project with Randolph Blake and Rene Marois investigated individuals with lexical-chromatic synesthesia. For these individuals, achromatic words, letters, and digits give rise to reliable color percepts. In a series of studies, we demonstrated the perceptual reality of synesthetic colors.

Click here for some more information on synesthesia.

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