Bose Arpita, Wood Rosalind, Kiran Swathi
Department of Clinical Language Sciences, School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK.
Department of Speech, Language, and Hearing Sciences, Boston University, Boston, MA, USA.
Int J Lang Commun Disord. 2017 May;52(3):334-345. doi: 10.1111/1460-6984.12276. Epub 2016 Oct 21.
Verbal fluency tasks are included in a broad range of aphasia assessments. It is well documented that people with aphasia (PWA) produce fewer items in these tasks. Successful performance on verbal fluency relies on the integrity of both linguistic and executive control abilities. It remains unclear if limited output in aphasia is solely due to their lexical retrieval difficulties or has a basis in their executive control abilities. Analysis techniques, such as temporal characteristics of word retrieved, clustering and switching, are better positioned to inform the debate surrounding the lexical and/or executive control contribution for success in verbal fluency.
To investigate the differences in quantitative (i.e., number of correct words) and qualitative (i.e., switching, clustering and word-retrieval times) performances on animal fluency task as a function of time between PWA and healthy control speakers (CS).
METHODS & PROCEDURES: Animal fluency data for 60 s were collected from 34 PWA and 34 CS, and responses were time stamped. The 60-s period was divided into four equal intervals of 15 s each (i.e., 15, 30, 45 and 60 s). The number of correct words, cluster size, number of switches, within-cluster pause and between-cluster pause were evaluated as a function of four 15-s time intervals between PWA and CS.
OUTCOMES & RESULTS: Compared with CS, PWA produced fewer words, had smaller cluster sizes and switched a fewer number of times. A decrease in the number of switches correlated with an increase in between-cluster pause durations. PWA showed longer within- and between-cluster pauses than CS. The two groups showed specific differences in the temporal pattern of the responses: as time evolved both PWA and CS showed decreased productivity for the number of correct words, but PWA reached the asymptote earlier in the time course than CS, neither group showed a change in cluster size, and the number of switches decreased as a function of time only for CS.
CONCLUSIONS & IMPLICATIONS: The findings suggest that for PWA the search and retrieval process is less productive and more effortful. This is indicated by smaller cluster size, fewer switches associated with increased between-cluster pause durations, as well as overall slowed retrieval times for the words. This shows that the difficulties with verbal fluency performance in aphasia have a strong basis in their lexical retrieval processes, as well as some difficulties in the executive component of the task.
言语流畅性任务包含在广泛的失语症评估中。有充分文献记载，失语症患者（PWA）在这些任务中产出的项目较少。言语流畅性任务的成功完成依赖于语言能力和执行控制能力的完整性。目前尚不清楚失语症患者产出受限是否仅仅是由于他们的词汇检索困难，还是在其执行控制能力方面存在基础。诸如检索词的时间特征、聚类和转换等分析技术，更有助于为围绕词汇和/或执行控制对言语流畅性成功所做贡献的争论提供信息。
研究失语症患者（PWA）与健康对照者（CS）在动物流畅性任务上的定量（即正确单词数量）和定性（即转换、聚类和单词检索时间）表现随时间变化的差异。
从34名失语症患者和34名对照者收集60秒的动物流畅性数据，并对反应进行时间标记。60秒的时间段被分成四个相等的15秒间隔（即15秒、30秒、45秒和60秒）。将正确单词数量、聚类大小、转换次数、聚类内停顿时间和聚类间停顿时间作为失语症患者和对照者之间四个15秒时间间隔的函数进行评估。
与对照者相比，失语症患者产出的单词更少，聚类大小更小，转换次数更少。转换次数的减少与聚类间停顿持续时间的增加相关。失语症患者的聚类内和聚类间停顿时间比对照者更长。两组在反应的时间模式上存在特定差异：随着时间推移，失语症患者和对照者的正确单词数量产出率均下降，但失语症患者在时间进程中比对照者更早达到渐近线，两组的聚类大小均未显示出变化，并且仅对照者的转换次数随时间减少。
研究结果表明，对于失语症患者而言，搜索和检索过程效率较低且更费力。这表现为聚类大小更小、与聚类间停顿持续时间增加相关的转换次数更少，以及单词的整体检索时间变慢。这表明失语症患者言语流畅性表现的困难在其词汇检索过程中有坚实基础，并且在任务的执行部分也存在一些困难。
