City Research Online

Abstract

Background: It has been argued that perseveration type corresponds to the level of breakdown so that total perseveration (the repetition of a whole word) involves the reactivation of a previous word at the lexical level when the target word is not sufficiently activated. A blended perseveration (the repetition of part of a previous response) results from a failure of target activation at the phoneme level (e.g. Martin & Dell 2007). This is challenged by the occurrence of non-word total perseverations, as these cannot be lexical retrievals (Hirsh 1998). A further problem is the occurrence of long intervals between perseverations and their sources. Some authors have invoked semantic relationships to explain these intervals (e.g. Martin, Roach, Brecher & Lowery 1998).

Aims: This study examines the perseveration of two individuals with jargon aphasia in order to explore the proposal that while some perseveration may result from the reactivation of a recent response via the mechanisms described above, another mechanism exists whereby perseverative responses are built around default phonology, resulting in stereotypical errors.

Methodology and Procedures: Tests of naming, reading and repetition were administered. Responses were analysed to determine: the extent of perseveration; the occurrence of long intervals between perseverations and their sources; patterns of phoneme use; the occurrence of non-word total perseverations.

Outcomes and Results: Both individuals produced large numbers of perseverative responses. Lengthy intervals could not be explained by semantic relationships. For each participant, certain consonants were found to dominate the phoneme frequency distribution. Evidence was found of an interaction between the occurrence of perseveration and presence of these favoured consonants. The possibility that non-word total perseverations arose from a different source from word total perseverations was rejected because there was no significant difference in the use of the favoured phonemes between the two types.

Conclusion: The findings support the theory of two mechanisms for perseveration. The first is local, occurring when residual activation overrides incoming activation. This is confined to a single speech act and occurs closely after the original occurrence. The second type is global, occurring across different contexts over time. It occurs because of default phonology, available in the event of a dearth of incoming activation at the phoneme level. Both total and blended perseverations may result from this mechanism. Word total perseverations may be favoured because of feedback from the phoneme level to the lexical level. Ideas for future research and implications for intervention are discussed.

Publication Type:	Article
Publisher Keywords:	Science & Technology, Life Sciences & Biomedicine, Clinical Neurology, Neurosciences & Neurology, CLINICAL NEUROLOGY, Aphasia, Jargon aphasia, Perseveration, Stereotypy, Nonwords, SPEECH PRODUCTION, ERRORS, SPEAKERS, NEOLOGISMS
Subjects:	P Language and Literature > P Philology. Linguistics
Departments:	School of Health & Psychological Sciences > Language & Communication Science
SWORD Depositor:	Symplectic Administrator

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