Does phonological working memory impairment affect sentence comprehension? A study of conduction aphasia
Abstract:Background: The nature of the relation between phonological working memory and sentence comprehension is still an open question. This question has theoretical implications with respect to the existence of various working memory resources and their involvement in sentence processing. It also bears clinical implications for the language impairment of patients with phonological working memory limitation, such as individuals with conduction aphasia.
Aims: This study explored whether limited phonological working memory impairs sentence comprehension in conduction aphasia.
Methods & Procedures: The participants were 12 Hebrew-speaking individuals with conduction aphasia who, according to 10 recall and recognition span tasks, had limited phonological short-term memory in comparison to 296 control participants. Experiments 1 and 2 tested their comprehension of relative clauses, which require semantic-syntactic reactivation, using sentence–picture matching and plausibility judgement tasks. Experiments 3 and 4 tested phonological reactivation, using two tasks: a paraphrasing task for sentences containing an ambiguous word in which disambiguation requires re-accessing the word form of the ambiguous word, and rhyme judgement within sentences. In each task the distance between a word and its reactivation was manipulated by adding words/syllables, intervening arguments, or intervening embeddings.
Outcomes & Results: Although their phonological short-term memory, and hence their phonological working memory, was very impaired, the individuals with conduction aphasia comprehended relative clauses well, even in sentences with a long distance between the antecedent and the gap. They failed to understand sentences that required phonological reactivation when the phonological distance was long.
Conclusions: The theoretical implication of this study is that phonological working memory is not involved when only semantic-syntactic reactivation is required. Phonological working memory does support comprehension in very specific conditions: when phonological reactivation is required after a long phonological distance. The clinical implication of these results is that because most of the sentences in daily language input can be understood without phonological reactivation, individuals with phonological working memory impairment, such as individuals with conduction aphasia, are expected to understand sentences well, as long as they understand the meaning of the sentences and do not attempt to repeat them or encode them phonologically.
Document Type: Research Article
Affiliations: Language and Brain Lab,School of Education, Tel Aviv University, Tel Aviv, Israel
Publication date: March 1, 2012