Comments on articles by Botvinick et al. and Jacob et al. M. M. Botvinick, T. S. Braver, D. M. Barch, C. S. Carter, and J. D. Cohen (2001) implemented their conflict-monitoring hypothesis of cognitive control in a series of computational models. The authors of the current article first demonstrate that M. M. Botvinick et al.'s (2001)…

A model is presented that demonstrates that a random response to external constraint can produce results similar to those predicted by more complex models. Behavior that appears rational, optimal, or adaptive may truly be a random response to external constraint. Predictions based on this model may provide appropriate null hypotheses. (SLD)

The coincidence hypothesis predicts that dissimilarity between objects that differ on two separable dimensions is larger than predicted from their unidimensional differences on the basis of triangle inequality and segmental additivity. The coincidence hypothesis was supported in two-dimensional stimuli studies. (Author/CM)

Multinomial modeling--a methodology that can be used to measure and study cognitive processes--is discussed, and applications are presented. This statistically based technique involves estimating hypothetical parameters that represent the probabilities of unobservable cognitive events and is compatible with computational theories of cognition.…

The mechanisms of perceptual learning are analyzed theoretically, probed in an orientation-discrimination experiment involving a novel nonstationary context manipulation, and instantiated in a detailed computational model. Two hypotheses are examined: modification of early cortical representations versus task-specific selective reweighting.…

A descriptive model of how people make judgments under ambiguity is proposed. Two factors are reflected in the model: (1) the amount of ambiguity, which affects the size of the simulation, and (2) one's attitudes toward ambiguity. The model is tested in four experiments using individual and group analyses. (Author/LMO)