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Using lexical variables to predict picture-naming errors in jargon aphasia

Catherine Godbold1, Lotte Meteyard1, Carmel Houston-Price1 and Arpita Bose1*
  • 1 University of Reading, United Kingdom

Introduction Individuals with jargon aphasia produce fluent output which often comprises high proportions of non-word errors (e.g., maf for dog). Research has been devoted to identifying the underlying mechanisms behind such output. Some accounts posit a reduced flow of spreading activation between levels in the lexical network (e.g., Robson et al., 2003). If activation level differences across the lexical network are a cause of non-word outputs, we would predict improved performance when target items reflect an increased flow of activation between levels (e.g. more frequently-used words are often represented by higher resting levels of activation). This research investigates the effect of lexical properties of targets (e.g., frequency, imageability) on accuracy, error type (real word vs. non-word) and target-error overlap of non-word errors in a picture naming task by individuals with jargon aphasia. Method Participants were 17 individuals with Wernicke’s aphasia, who produced a high proportion of non-word errors (>20% of errors) on the Philadelphia Naming Test (PNT; Roach et al., 1996). The data were retrieved from the Moss Aphasic Psycholinguistic Database Project (MAPPD, Mirman et al., 2010). We used a series of mixed models to test whether lexical variables predicted accuracy, error type (real word vs. non-word) and target-error overlap for the PNT data. As lexical variables tend to be highly correlated, we performed a principal components analysis to reduce the variables into five components representing variables associated with phonology (length, phonotactic probability, neighbourhood density and neighbourhood frequency), semantics (imageability and concreteness), usage (frequency and age-of-acquisition), name agreement and visual complexity. Results and Discussion Table 1 shows the components that made a significant contribution to each model. Individuals with jargon aphasia produced more correct responses and fewer non-word errors relative to real word errors when items were phonologically simpler (shorter, more dense and higher frequency neighbourhoods), higher usage (higher frequency and earlier age-of-acquisition)and less visually complex. Correct responses were also more likely to be elicited by high name agreement targets. The strongest contribution was from the phonology and usage components. Target-error overlap in non-word errors was predicted only by phonology, with phonologically-simpler items predicting lower overlap. These results demonstrate that output in jargon aphasia is modulated by properties of target items. Increasing activation in the system improves output in predictable ways. As well as predicting an item’s susceptibility to error (e.g., increased error rates for longer, low density, low frequency, late acquired, low name agreement and high visual complexity items), we could predict the nature of the error on the basis of target characteristics (e.g., non-word errors more likely for longer, low density, low frequency, late acquired, high visual complexity items). Increasing the strength of the signal reaching the phonological level reduces the rate of non-word error production but can result in lower target-error overlap, perhaps due to increased competition between activated phonemes. These findings are considered within the context of current models of single word production (e.g., Dell et al., 1997).

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References

Dell, G. S., Schwartz, M. F., Martin, N., Saffran, E. M., & Gagnon, D. A. (1997). Lexical access in aphasic and nonaphasic speakers. Psychological Review, 104(4), 801–38.

Mirman, D., Strauss, T. J., Brecher, A., Walker, G. M., Sobel, P., Dell, G. S., & Schwartz, M. F. (2010). A large, searchable, web-based database of aphasic performance on picture naming and other tests of cognitive function. Cognitive Neuropsychology, 27(6), 495–504.

Roach, A., Schwartz, M. F., Martin, N., Grewal, R. S., & Brecher, A. (1996). The Philadelphia naming test: Scoring and rationale. Clinical Aphasiology, 24, 121-133.

Robson, J., Pring, T., Marshall, J., & Chiat, S. (2003). Phoneme frequency effects in jargon aphasia: A phonological investigation of nonword errors. Brain and Language, 85, 109–124.

Keywords: jargon aphasia, lexical variables, Picture-naming, mixed models, Principal Component Analysis

Conference: Academy of Aphasia 53rd Annual Meeting, Tucson, United States, 18 Oct - 20 Oct, 2015.

Presentation Type: platform paper

Topic: Student first author

Citation: Godbold C, Meteyard L, Houston-Price C and Bose A (2015). Using lexical variables to predict picture-naming errors in jargon aphasia. Front. Psychol. Conference Abstract: Academy of Aphasia 53rd Annual Meeting. doi: 10.3389/conf.fpsyg.2015.65.00063

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Received: 30 Apr 2015; Published Online: 24 Sep 2015.

* Correspondence: Dr. Arpita Bose, University of Reading, Reading, United Kingdom, a.bose@reading.ac.uk