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Title: Semantic processing in natural language understanding
Author: Lipka, Sigrid Ute
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 1993
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This thesis investigates the interaction between lexical and syntactic processing. In the first experiment the semantic priming effect was used to test the activation of basic semantic features which were defined on the basis of Jackendoff's (1983) theory. Priming of lexical decisions was studied in Experiment 1 with visually presented nouns. Priming effects were found for an SOA between prime and target of 400 ms but only for associatively related pairs. There was no priming for word pairs which shared basic semantic features but were not associated and did not reflect a highly typical script-based or functional relationship. Experiments 2 and 3 indicated that basic semantic features are processed rapidly during sentence comprehension and are automatically integrated with the sentence. Subjects were slowed when making lexical decisions on semantically violating words in syntactically well-formed sentences. The effects of semantic violations were confirmed in Experiments 4 and 4b using a self-paced reading task, and a self-paced reading task with continuous grammaticality judgements, respectively. Results of Experiment 4 also showed that the effect of pragmatic violations occurred later on in the sentence than did the effect of semantic violations, indicating that the two have different processing origins, each with a different time course. In Experiment 4b, semantic violations were judged to make the sentence ungrammatical more often than pragmatic violations. Using the two self-paced reading paradigms, Experiments 5, 6 and 7 showed that semantic features of subject and object nouns affect the size of the garden path effect when reading syntactically ambiguous sentences in which both a transitive and an intransitive analysis are temporarily possible. The results of the studies allow us to specify a model of the interactions of the semantic subsystem, the parser and the thematic subsystem, which contrasts both with a strong thematic model and a single-analysis model.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available