Issues surrounding the discreteness or continuity of cognitive processes have played a major role in experimental psychology, although there has been relatively little work that directly addresses these topics. Nevertheless, there has been a shift away from discrete models and toward continuous ones. The research reported in this article demonstrates discrete processing of information in an anagram task selected because of its similarity to insight problems, which seem subjectively to produce discrete "illumination" during processing. The authors used speed-accuracy decomposition (SAD), a relatively new technique for investigating the time course of information processing. The results of 2 experiments indicate little or no partial information in the anagram tasks, in contrast to previous research with SAD, all of which has revealed partial information. General models of human information processing must therefore be able to account for both patterns.

In the present study we examined whether semantic relations are atomistic unitary associations, or are complex concepts consisting of a number of relational elements. The complexity of the ownership relation was assessed by combining a relation verification task ("Many people own [cars/comets]") with the speed-accuracy decomposition procedure (Meyer, Irwin, Osman, & Kounios, 1988). The latter permits one to determine whether subjects achieve their final state of response accuracy in a single, discrete all-or-none transition, or whether the relevant processes yield partial information representing intermediate states of knowledge. The rationale was that the retrieval of a unitary relational link from a classical associative network should be an all-or-none affair. In contrast, a set of relational elements need not be processed as a unitary bundle, thereby allowing partial response-information states. In two experiments, we found evidence of such partial information (i.e., sensitivity in units of d'), lending support to the notion that relations are complex. Furthermore, the results suggest that the accumulation of guessing sensitivity was linear over time, weighing against alternate theoretical interpretations.

Cognitive theory posits association by juxtaposition or by fusion. We employed the measurement of event-related brain potentials (ERPs) to a concept fusion task in order to explore memory encoding of these two types of associations between word pairs, followed by a memory test for original pair order. Encoding processes were isolated by subtracting fusion task ERPs corresponding to pairs later retrieved quickly from ERPs corresponding to pairs later retrieved slowly, separately for pairs fused successfully and unsuccessfully (i.e., juxtaposed). Analyses revealed that the encoding of these two types of associations yields different ERP voltage polarities, scalp topographies, and brain sources extending over the entire time course of processing.

Speed-accuracy decomposition (SAD) is a relatively new technique for studying the time course of information processing. It uses information on both the temporal distributions and the accuracies of participants' responses to two types of trials to derive an estimate of the amount of partial information available to participants at specific points in processing. As a new technique, its range of applicability and robustness have not yet been fully determined. Simulations are reported here that investigate these issues, with simulated data sets, SAD analysis of same, and comparison of the SAD analysis results to the parameters used to generate the data.In general, SAD appears to be reasonably robust against certain violations of assumptions and a variety of unusual data patterns. It is recommended that future SAD studies be accompanied by simulations based on observed parameters to better understand the data obtained. Cognitive psychologists are frequently confronted by the fact that measures of mental functioning are necessarily limited and frequently indirect. Two commonly used measures are response time (RT) and ac-

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