Non-Symbolic Exact Quantity Representation in a Language Impaired Population


English-speakers whose access to number language is artificially compromised by verbal interference and the Pirahã (an Amazonian tribe without exact number words) appear to rely on analog magnitude estimation for representing non-symbolic exact quantities greater than 3. Here, 16 participants with aphasia performed the 5 counting tasks from these previous studies. Performance was poorest when targets were not visible during response (70% correct, task 4; 71% correct, task 5) and best when targets were presented as subitizable groups of 2 and 3 (98% correct, task 2). Western Aphasia Battery-Revised subtest scores correlated with task performance, suggesting diverse forms of language impairment may contribute to errors. Coefficients of variation for tasks and significant correlations of target magnitude with error rate (r2=.88) and error size (r2=.87) across tasks suggest participant use of analog magnitude estimation. Experiments involving people with aphasia may further refine our understanding of how language and thought interact.

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