Across four tasks, the sensitivity of advanced Persian Learners of
English as a Foreign Language (PLEFL) to the impact of thematic hierarchy on the choice of English sentence structure was tested. In recognition tasks, participants were presented with pairs of active and passive sentences constructed with the use oftheme-experiencer (such as amuse) and experiencer-theme (such as praise) verbs. In the production tasks, participants were presented with sets of two nouns and a verb (including both theme-experiencer and experiencer-th_me verbs) and requested to construct a sentence for each set. The dependent variable in all tasks was the syntactic form of the sentence preferred or produced by the participants. The results demonstrated that with theme-experiencer verbs, passives are more ftequent. This indicates that PLEFL place the more prominent thematic roles in the initial position of a sentence. The consequences of the findings of this study for perspectives on ultimate attainment are discussed.
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