An analysis of thematic and phrasal structure in people with aphasia: What more can we learn from the story of Cinderella?

Sentence production difficulties are a common feature of aphasia. The aim of the current study was to investigate the processes involved in sentence production. An analysis of sentence production was designed which described thematic, phrasal and morphological structure. The sentence production of 22 speakers with aphasia was compared to that of 20 normal speakers. The study investigated: (i) the consistency of difficulties across individual speakers with aphasia (ii) the patterns associated with non-fluent and fluent speech and (iii) the relationship between different aspects of sentence production. Extensive variability was seen in the group of people with aphasia. Individual non-fluent and fluent speakers had widely varying patterns of performance suggesting that speech fluency is not a useful diagnostic measure. The production of thematic structure was independent of phrasal structure suggesting that distinct processes are involved in their specification. The processes involved in the elaboration of phrasal structure and the production of grammatical morphemes were more closely associated. Some independence was seen between the measures associated with particular levels of structure suggesting there may be sub-processes involved which can also be selectively impaired in aphasia.