Introduction: Electrophysiological and neuroimaging studies suggest that regular and irregular verbs are differently represented in the brain. Findings from studies of patients seem to agree with this view, but there are discordant data.
Aim: To test if there is a dissociation in regular and irregular verb processing between patients with anterior lesions, characterized as Broca's aphasics, and patients with posterior lesions, characterized as anomics.
Patients and methods: 10 aphasic patients participated in the study: five presenting evidence of Broca's aphasia and five presenting evidence of anomia. The task required patients to complete 58 sentences with a verb conjugated in the past tense form. 29 sentences required an irregular verb and 29 required a regular verb.
Results: Statistical analyses indicate a main effect due to differences between the different types of patients, and an interaction between this effect of patient type and the effect of verb type. The interaction was due to the fact that anomic patients had more difficulty in completing sentences using irregular verbs.
Conclusions: The results of this study support a dual route model, which assumes that regular verbs are processed by application of morphological rules whereas irregular verbs are processed through the addressed recovery of conjugated forms.