A Disorder of Executive Function and Its Role in Language Processing

ABSTRACT

R. Martin and colleagues have proposed separate stores for the maintenance of phonological and semantic information in short-term memory. Evidence from patients with aphasia has shown that damage to these separable buffers has specific consequences for language comprehension and production, suggesting an interdependence between language and memory systems. This article discusses recent research on aphasic patients with limited-capacity short-term memories (STMs) and reviews evidence suggesting that deficits in retaining semantic information in STM may be caused by a disorder in the executive control process of inhibition, specific to verbal representations. In contrast, a phonological STM deficit may be due to overly rapid decay. In semantic STM deficits, it is hypothesized that the inhibitory deficit produces difficulty inhibiting irrelevant verbal representations, which may lead to excessive interference. In turn, the excessive interference associated with semantic STM deficits has implications for single-word and sentence processing, and it may be the source of the reduced STM capacity shown by these patients.

KEYWORDS

Semantic short-term memory - executive function - aphasia

REFERENCES

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1 There is considerable controversy over the extent to which a phonological STM deficit has any consequences for comprehension. Although Vallar and Baddeley [36] demonstrated that their patient PV had difficulty with long, semantically reversible sentences, studies with other such patients have found good comprehension for these sentence types and for other sentences with complex syntactic structures. [37]