Localizing the deficit in a case of jargonaphasia

Abstract

We report the case of a neologistic jargonaphasic and ask whether her target-related and abstruse neologisms are the result of a single deficit, which affects some items more severely than others, or two deficits: one to lexical access and the other to phonological encoding. We analyse both correct/incorrect performance and errors and apply both traditional and formal methods (maximum-likelihood estimation and model selection). All evidence points to a single deficit at the level of phonological encoding. Further characteristics are used to constrain the locus still further. V.S. does not show the type of length effect expected of a memory component, nor the pattern of errors associated with an articulatory deficit. We conclude that her neologistic errors can result from a single deficit at a level of phonological encoding that immediately follows lexical access where segments are represented in terms of their features. We do not conclude, however, that this is the only possible locus that will produce phonological errors in aphasia, or, indeed, jargonaphasia.

We would like to thank V.S. for all her help, cooperation and good humour throughout the study. Part of this research was done for the PhD dissertation of the third author. We are grateful for the comments of Alfonso Caramazza and three anonymous reviewers. Funding for patient transport was provided by the University of Birmingham, Behavioural Brain Sciences Centre.

Notes

¹ Technically, the prediction is of a mixture distribution, and we test this hypothesis. The clearest type of mixture would be a bimodal distribution.

²In addition, it is unclear why Schwartz et al. apparently allow normal slips of the tongue to have a source after the level of phonological encoding but exclude this level as a possible source of aphasic errors (see their treatment of movement errors, Schwartz et al. 2004, p. 161).