Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

Program Name/Specialization

Cognitive Neuroscience

Faculty/School

Faculty of Science

First Advisor

Dr. Todd Ferretti

Advisor Role

Advisor

Abstract

As we read, we develop mental models of the discourse content called situation models. Situation models are integral to how we keep track of information, and to do so in an ongoing event incoming information needs to be integrated into the model or discarded. The type of information being presented, and its relation to prior data, impacts how that new information is processed. The current research examined discourse passages containing concepts that were either previously mentioned (match), mentioned with a general term (general category), unmentioned in lieu of another concept (mismatch), or completely unmentioned previously (indeterminate), and examined how these four target/antecedent relation types were integrated. Before this research these four types of relations had never been directly compared in one experiment and as such, the current work aimed to establish a baseline for the mental processing of these relations during online reading tasks.

In Chapter 2 the four aforementioned types of relations were examined in two ways: through event-related potential (ERP) technology and sentence completion surveys. The ERP analysis was performed to observe what happens within the brain during reading as it happens. The sentence completions were implemented to provide insight into howreaders incorporated these discourse concepts into their situation models. In this chapter the target stimuli were always preceded by the definite article The, which adds a certain level of contextual constraint by presupposing that the referent already exists within the situation model. The N400 amplitudes showed that the mismatch and the indeterminate relations were the least congruent with the provided discourse. The extended N400 results indicated that the indeterminate relations showed the highest cost of integration into the situation model, compared to the match, mismatch, and general category relations.

Chapter 3 applied the exact same methodologies as Chapter 2, but instead had the target stimuli preceded by the indefinite article A/An. The goal of these experiments was to determine what, if any, differences became apparent when an indefinite article was used to indicate the target stimuli, rather than a definite article. Indefinite articles are not as contextually constraining as definite articles and therefore may allow for more open interpretation of the four target/antecedent relation types. It was found that when presented with an indefinite article, targets in the indeterminate condition had the least semantic congruency with developing situation models, less so even than the mismatching information, as shown by the N400 amplitudes. The sentence completions results indicated that the indefinite article led to slightly more variability in how concepts were integrated into the situation model than the definite article. General category targets were much less likely to be considered coreferential with the relevant antecedent when an indefinite article was used. This finding aligns with the overall increase in semantic availability (less negative N400) following indefinite article use, particularly with the general category relations.

In Chapter 4 the same ERP methodology and stimuli as seen in Chapter 2 were again used, however the visual hemifield technique (VHF) was applied to allow for comparison of processing between the left (LH) and right hemispheres (RH). It was found that the indeterminate relations were more difficult semantically to integrate into the situation models than the mismatching relations, but only in the LH and not the RH, where they did not differ. There was no difference found in the integration cost between the indeterminate, mismatching, or general category concepts. These findings support the idea that both hemispheres are required for the processing of such nuances and therefore to optimal discourse processing as a whole.

Overall, this dissertation provides novel neurocognitive data on how people integrate discourse concepts into situation models during language processing, both across and between the cerebral hemispheres. The sentence completion results provided insight into what exactly the examined ERP components express in the process of situation model development. By examining the definite and indefinite articles, this dissertation emphasized the importance of grammatical nuances on the ease of mental processing, as well as how it may influence what information is integrated or not in the situation model.

Convocation Year

2022

Convocation Season

Spring

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