Dataset Information

Lexical processing depends on sublexical processing: Evidence from the visual world paradigm and aphasia.

ABSTRACT: Some early studies of people with aphasia reported strikingly better performance on lexical than on sublexical speech perception tasks. These findings challenged the claim that lexical processing depends on sublexical processing and suggested that acoustic information could be mapped directly to lexical representations. However, Dial and Martin (Neuropsychologia 96: 192-212, 2017) argued that these studies failed to match the discriminability of targets and distractors for the sublexical and lexical stimuli and showed that when using closely matched tasks with natural speech tokens, no patient performed substantially better at the lexical than at the sublexical processing task. In the current study, we sought to provide converging evidence for the dependence of lexical on sublexical processing by examining the perception of synthetic speech stimuli varied on a voice-onset time continuum using eye-tracking methodology, which is sensitive to online speech perception processes. Eight individuals with aphasia and ten age-matched controls completed two visual world paradigm tasks: phoneme (sublexical) and word (lexical) identification. For both identification and eye-movement data, strong correlations were observed between the sublexical and lexical tasks. Critically, no patient within the control range on the lexical task was impaired on the sublexical task. Overall, the current study supports the claim that lexical processing depends on sublexical processing. Implications for inferring deficits in people with aphasia and the use of sublexical tasks to assess sublexical processing are also discussed.

SUBMITTER: Dial HR

PROVIDER: S-EPMC6615952 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Lexical processing depends on sublexical processing: Evidence from the visual world paradigm and aphasia.

Dial Heather R HR McMurray Bob B Martin Randi C RC

Attention, perception & psychophysics 20190501 4

Some early studies of people with aphasia reported strikingly better performance on lexical than on sublexical speech perception tasks. These findings challenged the claim that lexical processing depends on sublexical processing and suggested that acoustic information could be mapped directly to lexical representations. However, Dial and Martin (Neuropsychologia 96: 192-212, 2017) argued that these studies failed to match the discriminability of targets and distractors for the sublexical and lex ...[more]

PMID: 30945141

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Project description:Individuals with aphasia frequently show lexical retrieval deficits due to increased interference of semantically related competitors, a phenomenon that can be observed in tasks such as naming pictures grouped by semantic category. These deficits are explained in terms of impaired semantic control, a set of abilities that are to some extent dependent upon executive control (EC). However, the extent to which semantic control abilities can be affected in a second and non-dominant language has not been extensively explored. Additionally, findings in healthy individuals are inconclusive regarding the degree to which semantic processing is shared between languages. In this study, we explored the effect of brain damage on semantic processing by comparing the performance of bilingual individuals with aphasia on tasks involving semantic control during word production and comprehension. Furthermore, we explored whether semantic deficits are related to domain-general EC deficits. First, we investigated the naming performance of Catalan-Spanish bilinguals with fluent aphasia and age-matched healthy controls on a semantically blocked cyclic naming task in each of their two languages (Catalan and Spanish). This task measured semantic interference in terms of the difference in naming latencies between pictures grouped by the same semantic category or different categories. Second, we explored whether lexical deficits extend to comprehension by testing participants in a word-picture matching task during a mixed language condition. Third, we used a conflict monitoring task to explore the presence of EC deficits in patients with aphasia. We found two main results. First, in both language tasks, bilingual patients' performances were more affected than those of healthy controls when they performed the task in their non-dominant language. Second, there was a significant correlation between the speed of processing on the EC task and the magnitude of the semantic interference effect exclusively in the non-dominant language. Taken together, these results suggest that lexical retrieval may be selectively impaired in bilinguals within those conditions where semantic competition is higher, i.e.,- in their non-dominant language; this could possibly be explained by an excessive amount of inhibition placed upon this language. Moreover, lexico-semantic impairments seem to be at least somewhat related to conflict monitoring deficits, suggesting a certain degree of overlap between EC and semantic control.

Dataset Information

Lexical processing depends on sublexical processing: Evidence from the visual world paradigm and aphasia.

Publications

Lexical processing depends on sublexical processing: Evidence from the visual world paradigm and aphasia.

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