Lexical retrieval of complex predicates in an agrammatic aphasic subject's sentence production

Abstract

In this paper we report on the investigation of those factors whichhave a role in the lexical selection of complex predicates, verbal modifier+verbconstructions, in the sentence production of a Hungarian agrammatic Broca'saphasic speaker. Two variables were investigated (i) the lexical representationalcomplexity of VM+V units: the target complex predicates contained a prefixalpreverb or argumental preverbs and (ii) syntactic complexity of the sentencesinto which the complex predicates were mapped: the target sentences were neu-tral and non-neutral sentences. Two methods were used, sentence anagram andsentence repetition tasks. The results indicate that the vulnerable part ofthe complex predicate is the Verbal Modifier part. In reproducing sentencesverbatim, VM errors occurred in higher proportion than base V errors. VM omissionand substitution errors were found only in non-neutral sentences and in neutralsentences modified by a sentential adverb. In sentences containing operatorsa verb movement effect was found: the proportion of VM substitution errorswas significantly higher in those sentences which contained focussed, wh-and negated constituents. Error rates of VMs were much lower in sentenceswhich contained universal quantifier phrases. The data suggest that the lexicalretrieval of complex predicates correlates with a syntactic operation, verbmovement to F. It can be assumed that there is a trade-off between the lexicalretrieval of complex predicates and the use of verb raising to Focus head,if the resource capacity is limited within the impaired sentence productionsystem. Verb movement to F can be achieved at the cost of incomplete lexicalaccess to complex predicates. The semantic type of VMs also had an efiecton the lexical retrieval of complex predicates: prefixed verbs are less vulnerablethan complex predicates containing argumental preverbs, predicative complementand bare noun types of verbal modifiers.