Purpose: The purpose of this study was to investigate how people with nonfluent aphasia produce semantically weighted verbs compared to people without aphasia, as well as how a discourse elicitation task affects verb production in people with nonfluent aphasia and people without aphasia.
Method: This study included 30 people with nonfluent aphasia and 32 age-matched people without aphasia from AphasiaBank. Language samples of five different discourse tasks were obtained and coded for heavy, light, and be-copular verbs. The number of verbs per utterance and the proportion of heavy, light, and be-copular verbs were compared between groups and between tasks.
Results: People with nonfluent aphasia showed a similar proportion of heavy verbs but reduced verbs per utterance and proportion of light verbs compared to people without aphasia. With regard to discourse task effects, we found a trend for a higher proportion of heavy verbs in sequential picture descriptions, and a higher proportion of be-copular verbs and lower proportion of heavy verbs for a recount compared to other tasks in people without aphasia. The discourse task effects were minimally found in people with nonfluent aphasia.
Conclusions: Our results suggest that people with nonfluent aphasia present with relatively preserved heavy verb production but with impaired production of light verbs in discourse. In addition, it appears that discourse tasks do not significantly influence the type of verbs produced by people with nonfluent aphasia possibly due to the floor effects and wide range of individual variability. This study is a preliminary effort to evaluate methodological factors that impact verb production; future studies are needed to develop a framework for clinical decision making when selecting a discourse elicitation task for people with aphasia.