The Center For Cognitive Science Cognitive Science Colloquium Wednesday, 2 March, 2:00 P.M. 280 Park Hall Richard L. Lewis Department of Psychology & Department of Linguistics University of Michigan Bounded Optimality in Language, Thought, and Action: Adaptation under Cognitive Constraint and Its Implications for Understanding Individual Differences In this presentation, we explore a theoretical framework that construes cognitive and linguistic processing as boundedly optimal control problems—as rational processes constrained by both the structure of the external environment and the structure and limitations of the cognitive architecture. Underlying the approach are computational methods for evaluating large spaces of possible behavioral strategies in terms of their expected utility given these constraints, rather than their fit to observed data. We demonstrate the generality of the approach through its application to elementary dual-tasking, "fast-and-frugal" decision making, verbal short-term memory, and eyemovement control in reading. A key theoretical payoff is an understanding of individual differences in performance as the empirical signatures of strategies that are adaptations to individually varying processing constraints. We discuss how the framework builds on and complements related approaches, including rational analysis, bounded rationality, Bayesian modeling, architectures, reinforcement learning, and signal-detection theory. The key feature of bounded optimality is the theoretical role assigned to processing constraints: They are used to help define the optimization problem, rather than used to explain departures from optimality. RECOMMENDED READING: Howes, Andrew; Lewis, Richard L.; & Vera, Alonso (2009), "Rational Adaptation under Task and Procesing Constraints: Implications for Testing Theories of Cognition and Action", Psychological Review 116(4): 717–751.