Insights into recurrent perseverative errors in aphasia: A case series approach

Abstract

Background: Recurrent perseverative errors are most commonly produced by speakers with aphasia (Albert & Sandson, 1986 Albert, M. L. and Sandson, J. 1986. Perseveration in aphasia.. Cortex, 22: 103–115. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). While some research has proposed that recurrent perseverative errors are primarily caused by an impaired ability to inhibit a prior response, most recent research proposes that these errors occur as a direct result of underlying language impairment at any specified processing level (e.g., Cohen & Dehaene, 1998 Cohen, L. and Dehaene, S. 1998. Competition between past and present: Assessment and interpretation of verbal perseverations.. Brain, 121: 1641–1659. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Aims: This investigation was designed to further explore the hypothesis that the type of recurrent perseverative errors produced reflects the level of language‐processing breakdown. Two specific questions were addressed: (1) Is the distribution of types of perseverative error similar to that of non‐perseverative errors within different language tasks? (2) Do the relative proportions of total and blended perseverative errors reflect an individual's language‐processing profile? Methods & Procedures: The recurrent perseverative error patterns of five individuals with aphasia with varying levels of language‐processing breakdown were examined across three language tasks (repetition, reading aloud, and picture naming). Outcomes & Results: The incidence of different types of recurrent perseverative errors was found to be influenced by the processing demands of individual tasks, relative to each participant's language‐processing breakdown. However, certain findings challenged current theories, such as the large proportion of perseverative errors that were unrelated to their targets and some participants' entire reproduction of prior neologisms across different responses. Different theoretical accounts are explored to attempt to understand these error patterns. Conclusions: This study supports theories proposing that recurrent perseverative errors are a direct result of underlying language‐processing breakdown in aphasia (Cohen & Dehaene, 1998 Cohen, L. and Dehaene, S. 1998. Competition between past and present: Assessment and interpretation of verbal perseverations.. Brain, 121: 1641–1659. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]; Martin, Roach, Brecher, & Lowery, 1998 Martin, N., Roach, A., Brecher, A. and Lowery, J. 1998. Lexical retrieval mechanisms underlying whole‐word perseveration errors in anomic aphasia.. Aphasiology, 12: 319–333. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). It is argued that examination of both whole word (total) and phoneme (blended) perseverative errors is necessary for a comprehensive analysis of the proposed relationship between perseveration and language‐processing impairment.