An evaluation of a computational model of lexical access: comment on Dell et al. (1997)

The computational model of lexical access proposed by G. S. Dell, M. F. Schwartz, N. Martin, E. M. Saffran, and D. A. Gagnon (1997) is evaluated. They argued that fits of their model to naming data obtained from normal and brain-damaged patients support assumptions regarding interactivity in the lexicon, global damage in aphasia, and continuity between normal and aphasic naming behavior. Additional analysis reveals that the model fits the empirical data poorly and that the claims Dell et al. made on the basis of the model's performance would not follow even if the model were accurate. Although use of a novel automatic regression procedure improved the model's fit, it cannot account for 5 of Dell et al.'s 21 patients (24%), and its limitations were found to be inherent in its design. It is argued that claims such as those made by Dell et al. can only be addressed by considering evidence from multiple related tasks and by comparing multiple computational models.