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In general, words are read aloud more rapidly than nonwords (Forster & Chambers, 1973; Frederiksen & Kroll, 1976). This “lexicality effect” can be seen as an extension of the standard frequency effect: Pronounceable nonwords are essentially very low frequency words. Coltheart et al. (2001) counted the lexicality effect among the phenomena their model simulated correctly. Again, however, the model’s behavior differed substantially from people’s.

This point can be illustrated by examining the distributions of naming latencies for words and nonwords from a study by Rastle and Coltheart (1999). Words were named faster than nonwords (the “lexicality” effect”), but the distributions of naming times overlap. As in this case, a statistically significant difference between two means does not indicate that all members of one group differed from all members of the other. (See supplemental materials.)

The DRC model’s performance on Rastle and Coltheart’s stimuli also exhibits a difference between the word and nonword means, consistent with the claim that the model reproduces the lexicality effect. However, the distributions are completely non‐overlapping. The model incorrectly predicts that all words from the study should have been named faster than all nonwords. The subjects read aloud simple nonwords such as rop and scup more rapidly than difficult words such as isle and scythe, but the DRC model produced the opposite result. The anomaly occurs because the lexical route yields phonological output more quickly than the nonlexical route even for odd words.

Accommodating these results again seems to require changing parameters in the model to slow the lexical route or to speed the nonlexical route, which produces undesirable side effects (lexicalizations of nonwords or regularizations of exception words). Moreover, changing parameters in the model to account for one phenomenon spoils the simulations of other phenomena (Seidenberg & Plaut, 2006).