Background: Individuals with Broca's aphasia show better performance on nouns than on verbs, but the distinction between nouns and verbs is not always clear; some verbs are conceptually and/or phonologically related to nouns, while others are not. Inconsistent results on effects of noun-verb relatedness on verb production have been reported in the literature.
Aims: We investigated (1) whether verb instrumentality (a conceptual relationship to nouns) or homonymy (a phonological relationship to nouns) would affect verb production in individuals with Broca's aphasia and (2) whether conceptual/phonological noun-verb relationship would affect responsiveness to aphasia therapy that focused on verb production.
Methods & Procedures: Three English-speaking individuals with Broca's aphasia produced 96 verbs in sentences in response to picture stimuli. The target verbs included those that use an instrument and those that do not (e.g., to hammer vs. to yawn) and verbs that are phonologically identical to a related noun (e.g., to comb vs. a comb), morpho-phonologically related to a noun (e.g., to grind vs. a grinder) and those that are not morphologically related to a noun (e.g., to lean). The participants' verb retrieval ability was assessed before and after a 4-week period of aphasia therapy.
Outcomes & Results: The participants produced more accurate instrumental than non-instrumental verbs both pre- and post-treatment. They also produced more verbs correctly that are homonyms with nouns than verbs that are phonologically related or unrelated to nouns before treatment. However, the effect of homonymy was not observed following treatment.
Conclusion: Individuals with Broca's aphasia were more accurate in their production of verbs that were conceptually and phonologically related to nouns than on verbs that were not. The performance of verb production improved significantly after therapy. We interpret the results to indicate that, whereas prior to treatment, the participants relied on phonologically related nouns to retrieve the target verbs, this reliance on knowledge of nouns decreased following therapy that was designed to improve verb production.