Word Production from the Perspective of Speech Errors in Aphasia

The central thesis of this chapter is that data from aphasia provide a key link between behavioral studies of speech errors and neurocognitive models of language production. We describe a body of research that uses the interactive two-step model to characterize the cognitive machinery of lexical access and simulate aphasic speech error patterns in naming and repetition. The model incorporates a two-step lexical access process and a nonlexical process for accessing phonology directly from auditory input. It attributes the variety of aphasic error patterns to variation in model parameters. In a final step, we have used voxel-based lesion analysis to map the lesion correlates of error patterns and parameters in large numbers of individuals, thereby linking model processes and brain areas. This work complements and extends contemporary neurocognitive accounts of language and brain, demonstrating that aphasia research is as central to theory development today as it has been historically.