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Grammatical number agreement processing using the visual half-field paradigm: an event-related brain potential study
Laura Kemmer1, Seana Coulson1, Marta Kutas2
1Department of Cognitive Science, University of California, San Diego, La Jolla, CA, USA.
Summary
The right hemisphere shows a distinct advantage in processing morphologically marked grammatical errors, while both hemispheres handle lexical agreement violations similarly. This research explores hemispheric differences in syntactic processing.
Area of Science:
- Neuroscience
- Psycholinguistics
- Cognitive Science
Background:
- Previous research suggests right hemisphere (RH) involvement in syntax, but evidence from intact brains is limited.
- Grammatical number agreement, marked lexically or morphologically, provides a test case for hemispheric specialization.
- The visual half-field paradigm allows for assessment of left hemisphere (LH) and RH processing in healthy adults.
Purpose of the Study:
- To investigate the role of each hemisphere in processing grammatical number agreement violations.
- To compare the processing of lexically versus morphologically marked agreement errors.
- To determine if syntactic processing differs between the hemispheres in individuals with intact brains.
Main Methods:
- Utilized the visual half-field paradigm with healthy adults to present grammatical number agreement stimuli.
- Examined processing of lexically marked reflexive pronoun agreement (e.g., herself/themselves) and morphologically marked subject-verb agreement (e.g., develop/develops).
- Collected behavioral data (response times, accuracy) and event-related potentials (ERPs) to analyze brain responses.
Main Results:
- Lexical agreement violations showed similar processing in both hemispheres, regardless of visual field presentation.
- Morphological agreement violations presented a left hemisphere advantage, with longer response times and reduced accuracy in the left visual field (LVF).
- Event-related potential (ERP) data revealed distinct patterns: P600 effects for lexical violations occurred in both visual fields, while P600 for morphological violations were observed only in the right visual field (RVF).
Conclusions:
- Both hemispheres can process lexically marked agreement violations similarly.
- Morphologically marked subject-verb agreement errors demonstrate a distinct left hemisphere specialization.
- These findings highlight hemispheric differences in syntactic processing, particularly for morphologically based grammatical structures.
