Target/error overlap in jargonaphasia: The case for a one-source model, lexical and non-lexical summation, and the special status of correct responses

Abstract

We present three jargonaphasic patients who made phonological errors in naming, repetition and reading. We analyse target/response overlap using statistical models to answer three questions: 1) Is there a single phonological source for errors or two sources, one for target-related errors and a separate source for abstruse errors? 2) Can correct responses be predicted by the same distribution used to predict errors or do they show a completion boost (CB)? 3) Is non-lexical and lexical information summed during reading and repetition? The answers were clear. 1) Abstruse errors did not require a separate distribution created by failure to access word forms. Abstruse and target-related errors were the endpoints of a single overlap distribution. 2) Correct responses required a special factor, e.g., a CB or lexical/phonological feedback, to preserve their integrity. 3) Reading and repetition required separate lexical and non-lexical contributions that were combined at output.

Sources of Phoneme Errors in Repetition: Perseverative, Neologistic, and Lesion Patterns in Jargon Aphasia

“…Psycholinguistic models account for non-word errors in Jargon aphasia through a breakdown in phonological encoding, whereby activation is not effectively transferred from the lexical to the phonological level (Schwartz et al, 2004; Marshall, 2006; Olson et al, 2007, 2015; Dell, 2014). Therefore, phonological and neologistic errors are accounted for by the same mechanism with differing degrees of breakdown severity.…”

“…There has been considerable research into the underlying causes of non-word and perseverative errors in repetition and other production modalities. Much evidence points to a single impairment source for paraphasias, neologisms and perseverative errors, with different error types reflecting a range of severity (Dell et al, 1997; Schwartz et al, 2004; Martin and Dell, 2007; Olson et al, 2007, 2015; Buckingham and Buckingham, 2011). The predominant hypothesis indicates a disruption in lexical and phonological processes, during which weak and aberrantly spreading activation can result in non-target phonology being selected for production.…”

“…The predominant hypothesis indicates a disruption in lexical and phonological processes, during which weak and aberrantly spreading activation can result in non-target phonology being selected for production. Non-word production is modulated by word length and word frequency, suggestive of a single lexico-phonological source, generating errors with a range of severity (Olson et al, 2007, 2015; Nozari et al, 2010). Non-word accuracy range adheres to a normal distribution, thereby suggesting that a single underlying source generates errors of varying severity (Olson et al, 2007).…”