Evaluating behavioral and neuroimaging data on past tense processing

Jaeger, Lockwood, Kemmerer, Van Valin, Murphy, and Khalak 1996 (Language 72.3) reported an experimental study that provided reaction time and PET neuroimaging data said to support Pinker's (1991) theory of inflectional morphology in which rule-governed forms and exceptions are processed by separate mechanisms. The results were also taken as evidence against connec tionist accounts in which a single processing system generates both types of forms. We provide a critical analysis of the study that yields three main conclusions: First, Jaeger ct al.'s data do not provide strong evidence that rule-governed forms and exceptions are processed in separate brain regions. Second, there are problems with the design of dhe study that contaminate critical comparisons between conditions. The results therefore afford alternative interpretations related to experiment-specific factors rather than the regular-irregular distinction. Third, the dissociations between rule-governed forms and exceptions observed in studies such as Jaeger er al.'s can be accommodated by the connectionist theory. We conclude by offering suggestions for future re search that would overcome the major limitations of this study and provide more decisive evidence bearing on the issues.*