Sentence Figurativeness and Modality Shape the Neural Bases of Language Processing
Dr. Gwenda Schmidt, Hope College
Confounding variables in stimuli may attribute to conflicting findings in the study of the neural processing of metaphorical language, including the modality (e.g. auditory, visual, etc.) of the word used metaphorically. Differences in brain activity due to modality would support an embodied account of cognition. To clarify the role of figurativeness (literal vs. metaphor) and modality in language processing, a highly controlled set of stimuli divided into three figurativeness conditions (literal, metaphor and anomalous) and two modality conditions (auditory and motion) was used. The dependent measure was the N400 amplitude, an event-related potential (ERP) component 400 ms post-stimulus which indexes semantic processing difficulty. It is derived form electroencephalographic (EEG) recordings at the scalp. Both figurativeness and modality were predicted to affect the size and scalp distribution of the N400 amplitude. Sentences included auditory literal (“His comeback was a haughty snort”), auditory metaphor (“Her limousine was a privileged snort”), motion literal (“The blow was a single punch”), motion metaphor (“The editorial was a brass-knuckle punch”), and anomalous. Sixteen right-handed native English speakers indicated which figurativeness category (literal, metaphor, or anomalous) they believed the sentences belonged. A repeated measures ANOVA revealed greater N400 amplitudes for metaphorical sentences than literal sentences. However, this effect may be confounded by the familiarity, naturalness, and imageability of the sentences. An interaction between figurativeness and modality was educed by literal auditory sentences producing greater N400 amplitudes than literal motion sentences, whereas motion metaphors produced greater N400 amplitudes than auditory metaphors. Furthermore, an interaction between modality and electrode site derived from greater N400 amplitudes for motion based sentences seen in the left posterior and left central electrode sites. These findings provide evidence to support an embodied, sensory-motor account of language, modulated by figurativeness and support the need for controlled stimuli regarding familiarity, naturalness, imageability, and modality factors.
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