E. Hazeltine, D. Teague, and R. B. Ivry have presented data that have been interpreted as evidence against a central bottleneck. This article describes simulations of their Experiments 1 and 4 in the ACT-R cognitive architecture, which does possess a central bottleneck in production execution. The simulation model is capable of accounting for the…

A memory-based scaling model--ANCHOR--is proposed and tested. The perceived magnitude of the target stimulus is compared with a set of anchors in memory. Anchor selection is probabilistic and sensitive to similarity, base-level strength, and recency. The winning anchor provides a reference point near the target and thereby converts the global…

Several computer simulation models of memory represent human knowledge in terms of labeled networks of interconnected ideas. This article attempted to learn in such models how these networks are searched to retrieve relevant information. (Author/RK)

Discusses research on mechanisms that determine the temporal properties of the retrieval of information, represented in long-term memory as a network of associations among concepts. A theory is developed concerned with processes leading from presentation of a probe to levels of activation in the network. (JN)

Adaptive control of thought-rational (ACT-R; J. R. Anderson & C. Lebiere, 1998) has evolved into a theory that consists of multiple modules but also explains how these modules are integrated to produce coherent cognition. The perceptual-motor modules, the goal module, and the declarative memory module are presented as examples of specialized…

The author analyzes some recent developments in the debate over the status of mental imagery. He attempts to specify what a propositional theory is, and considers arguments for and against the imagery position, i.e., whether visual imagery is encoded in terms of properties that are quite spatial and modality specific. (Author/RK)

Research on intelligent tutoring seeks to develop systems for automating education and to explore epistemological issues concerning the nature of the knowledge presented by tutors and how that knowledge can be learned. The ACT theory of skill acquisition and its successor (PUPS--PenUltimate Production System) provides production-system models of…