Comparison of single-word therapy versus sentence therapy for verb retrieval and sentence production in Broca’s aphasia

Abstract

Background: In the existing literature, verb therapy studies take one of two approaches regarding verb retrieval: (1) the single-word level, in which verbs are treated similarly to nouns, and (2) the sentence level, which emphasises the relationship between verbs and nouns in a sentence. Few studies have directly compared the efficacy of both the approaches.

Aims: The primary aim of this article is, first, to compare the efficacy of single-word therapy versus sentence therapy for verb retrieval and, second, to examine the impact of each type of therapy on single-word and sentence production in connected speech.

Methods & Procedures: Using a single-subject crossover within-subjects design, six participants with Broca’s aphasia were trained to retrieve verbs under two therapy conditions: single-word therapy and sentence therapy. Additionally, a connected speech task was administered in the baseline phase and after each therapy condition. The impact of the two therapies on sentence production was measured using the samples derived from the connected speech.

Outcomes & Results: At the group level, all six participants showed highly significant and equal improvement in verb retrieval after receiving both the types of therapy. However, at the individual level, participants were found to show different results compared with the overall group tendency. One participant benefited more from single-word therapy than sentence therapy, while another showed the reverse pattern. At the group level, in connected speech the number of grammatical sentences, especially single-argument structure sentences, and the number of verbs increased significantly after single-word therapy. After sentence therapy, however, there was no significant change in mean length of utterance (MLU), the number of grammatical sentences and the number of verbs.

Conclusions: At the group level, verb retrieval in participants with Broca’s aphasia improved significantly after both the types of therapy. For connected speech, however, only single-word therapy brought about significant changes.

Keywords:

• Broca’s aphasia
• verb therapy
• verb retrieval
• connected speech
• sentence production

Notes

1. We included individuals with resolved aphasia in the control group because their total scores were in the range of one standard deviation of the mean of 150 non-aphasic individuals obtained from the Japanese aphasia battery, SLTA.

2. Only data from participants P2–P6 were entered into the statistical analyses because the number of verbs and criterion level for verb training for P1 were different from those for the remaining participants.