Closed-class words as first syllables do interfere with lexical decisions for nonwords: implications for theories of agrammatism.
It has been proposed that a principal cause of the agrammatism of some Broca's aphasics is that such patients, unlike normal subjects, are unable to make use of a special retrieval mechanism for closed-class ("function") words (D. C. Bradley, 1978, Computational distinctions of vocabulary type, Unpublished Ph.D. thesis; D. C. Bradley, M. F. Garrett, & E. B. Zurif, 1980. In D. Caplan (Ed.), Biological studies of mental processes). The main evidence for the existence of such a mechanism consisted of two observations: (1) the recognition of open-class words was observed to be frequency-sensitive, but that of closed-class words was not; and (2) lexical decisions for nonwords which began with open-class words were delayed, whereas there was no such interference for nonwords which began with closed-class words. However, the first of these observations has proved nonreplicable (e.g., B. Gordon & A. Caramazza, 1982, Brain and Language, 15, 143-160, 1983, Brain and Language, 19, 335-345; J. Segui, J. Mehler, W. Frauenfelder, & J. Morton, 1982, Neuropsychologia, 20, 615-627), and in the present paper, three lexical decision experiments are reported in which it is found that, when certain confounding variables are controlled, nonwords which begin with closed-class words are subject to interference. Moreover, contrary to a suggestion of Kolk and Blomert (1985, Brain and Language, 26, 94-105) the interference is independent of the presence of closed-class items in the lexical decision word list. It seems, then, that closed-class words are not qualitatively different from open-class words with respect either to frequency sensitivity or to nonword interference, and in consequence, the above proposed explanation of agrammatism is left without major empirical support.
Petocz
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A
Department of Psychology, University of Sydney, N.S.W., Australia.
Oliphant
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G
D000293:Adolescent; D000328:Adult; D001037:Aphasia / Q000523:psychology*; D001039:Aphasia, Broca / Q000523:psychology*; D003657:Decision Making; D006801:Humans; D008037:Linguistics; D011932:Reading; D012660:Semantics