Agrammatic Broca's aphasia is not associated with a single pattern of comprehension performance

One influential hypothesis posits that the brain regions implicated in Broc a's aphasia are responsible for specific syntactic operations that are nece ssary for the comprehension and production of sentences (Grodzinsky, 1986, 1990, in press). The empirical basis of this hypothesis is the claim that B roca's aphasics have no difficulty understanding sentences in the active vo ice land other "canonical" sentence types, such as subject relatives and cl efts with agentive predicates), but perform at chance level with passive vo ice constructions land other "noncanonical" sentences such as object-gap re latives and object clefts). In the face of well established results indicat ing that Broca's aphasics can exhibit several different performance pattern s on these sentence types, Grodzinsky, Pinango, Zurif, and Drai (1999) argu ed that these conflicting results do not challenge the theory when the data are analyzed appropriately. They carried out a creative statistical analys is of the comprehension performance of published cases of Broca's aphasia a nd concluded that all of these cases are in agreement with the predicted pa ttern: chance on passives and 100% correct on actives. Here we show that th e statistical reasoning adopted by Grodzinsky et al. (1999) is flawed. We a lso show that the comprehension performance of a substantial number of the Broca's aphasics in their own sample does not conform to the pattern requir ed. Rather, contrary to these authors' claim, Broca's aphasia is not associ ated with a consistent pattern of sentence comprehension performance, but a llows for a number of distinct patterns in different patients. (C) 2001 Aca demic Press.