Research Interests

My research in mathematical psychology and cognitive science has focused on various fundamental aspects of human perception, attention, memory, language, thought, cognitive control, and action. During the early part of my career, I studied how people organize and retrieve information about concepts and meanings of words stored in long-term semantic memory. By measuring people's reaction times to recognize semantically related words, my experiments revealed and analyzed processes of automatic "spreading activation" whereby word meanings are accessed in mental networks of concepts. Subsequently, I have developed new general methods for investigating the quantitative temporal properties of mental information-processing stages under a broad range of conditions through examining probability distributions of reaction times. I have also created mathematical models to characterize the speed and accuracy of rapid aimed limb movements in terms of optimization processes that compensate for stochastic neuro-motor "noise". Integrating these various lines of investigation, my most recent research--conducted in collaboration with computer-science colleagues--has formulated a unified computational theory of cognition and applied it to account for numerous phenomena observed in human multi-tasking. A key objective of this theory is to explain and predict strategies that people use for task scheduling as a function of the types of task to be performed.

Membership Type


Election Year


Primary Section

Section 52: Psychological and Cognitive Sciences

Secondary Section

Section 28: Systems Neuroscience