An investigation of the interaction between thematic and phrasal structurein nonfluent agrammatic subjects

Garrett (1982) developed a model of normal sentence production which has be en used in the description of aphasic language (Schwartz, 1987). This study investigated the effects of the thematic representation specified at the f unctional level on the complexity of the phrases produced at the positional level. A group of 14 nonfluent, agrammatic subjects were compared to 20 no rmal controls in their production of the story of Cinderella. The agrammati c subjects produced fewer argument structures than the normal control subje cts. Their phrasal realization of the arguments, however, was not qualitati vely different from that of the normal subjects. In both cases, with an inc rease in the number of arguments, there was a concurrent increase in the me an complexity of the phrases used to realize those arguments and in the tot al phrasal complexity of the utterances. The complexity of noun phrases dif fered according to the thematic roles expressed; this seemed to be a conseq uence of their different locations in the sentence. Preverbal noun phrases were much less complex than postverbal noun phrases. There was no evidence to suggest that there was a trade-off between the production of thematic st ructure and subsequent phrasal production. Neither was there evidence to su ggest that production differed according to whether the phrase was an argum ent of the verb or a nonargument. The complexity of a phrase was determined by the type of information it conveyed. (C) 2001 Academic Press.