Effects of therapy targeted at verb retrieval and the realisation of the predicate argument structure: A case study

Abstract

Background : Verb retrieval and sentence production difficulties are both common features of aphasia. Previous treatment studies have focused predominantly on verb retrieval and the mapping of semantic and syntactic structure. There have been more limited investigations of the production of the predicate argument structure (PAS). Aims : This study aimed to evaluate the outcome of intensive therapy for a client with aphasia. NS had multiple and interacting difficulties that resulted in problems in producing sentences. Therapy aimed to improve his sentence production by: (a) improving the retrieval of verbs, (b) increasing his awareness of the relationship between nouns and verbs, and (c) improving his production of one-, two-, and three-argument structures. The therapy thus targeted access to PAS information and PAS production as well as verb retrieval. Methods & Procedures : A period of intensive therapy, based around a set of 48 self-selected verbs, was preceded and followed by detailed assessment of NS's single word and sentence production and comprehension. Outcomes & Results : Therapy resulted in a significant improvement in NS's retrieval of the verbs involved in treatment but no generalisation to other verbs. His production of sentences showed more widespread changes. He produced more nouns within sentences, omitted fewer obligatory arguments, and produced a greater variety of argument structures in connected speech. Conclusions : Therapy resulted in a greater awareness of the need for a verb within a sentence and a strategy for producing the argument structure frame around that verb. Improved sentence production was therefore seen, although verb retrieval difficulties were still evident. The study replicates previous research that verb and sentence production difficulties can be treated effectively in people with aphasia. The effects of therapy on sentence production in constrained tasks and narrative speech are discussed.