We present a new model for lexical decision, REM-LD, that is based on REM theory (e.g., Shiffrin & Steyvers, 1997). REM-LD uses a principled (i.e., 'Bayes' rule) decision process that simultaneously considers the diagnosticity of the evidence for the 'WORD' response and the 'NONWORD' response. The model calculates the odds ratio that the presented stimulus is a word or a nonword by accumulating likelihood ratios for each lexical entry in a small neighborhood of similar words. We report two experiments that used the signal-to-respond paradigm to obtain information about the time course of lexical processing. Experiment 1 verified the prediction of the model that the frequency of the word stimuli affects performance for nonword stimuli. Experiment 2 was done to study the effects of nonword lexicality, word frequency, and repetition priming and to demonstrate how REM-LD can account for the observed results. We discuss how REM-LD can be extended to account for effects of phonology such as the pseudohomophone effect, and how REM-LD can predict response times in the popular 'respond-when-ready' paradigm. Several other quantitative models of lexical decision are evaluated with respect to the findings reported here.

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Department of Psychology

Wagenmakers, E.-J., Steyvers, M., Raaijmakers, J., Shiffrin, R. M., van Rijn, H., & Zeelenberg, R. (2003). A Model for Evidence Accumulation in the Lexical Decision Task. Retrieved from http://hdl.handle.net/1765/1005