Metaphor Processing: Neural Responses to Figurativeness and Sensory Imagery
Dr. Gwenda Schmidt, Hope College
The distinction between metaphorical, literal, and anomalous language (called figurativeness) processing within the brain was investigated through the use of electroencephalography (EEG). In addition, neural distinctions of modality-specific language were examined by dividing the stimuli into auditory and motion modalities. In the auditory condition, sentences ended in nouns depicting sound (“clatter”), and in the motion condition, sentences ended in nouns depicting motion (“glide”). Therefore, the three figurativeness conditions (metaphor, literal, and anomalous) each included an equal amount of auditory and motion sentences. Before testing, sentences were matched on predictability, familiarity, naturalness, imageability, accuracy rates, and response times to eliminate confounding variables. Upper-class English majors (n = 11) were presented with 300 sentences. While the participants performed a semantic judgment task of categorizing the sentence as literal, metaphorical or anomalous, the neural activity within each brain quadrant (left anterior, right anterior, right posterior, left posterior) was recorded. The amplitude of the brain wave generated approximately 400 ms after the sentence presentation (called the N400) was the dependent variable used to examine differences in brain processing. A MANOVA revealed a main effect of modality on the N400 amplitudes, where the motion modality sentences produced greater amplitudes. There was also a significant interaction between figurativeness and the brain quadrants on the N400 amplitude. Lastly, there was a weak interaction effect between modality and figurativeness on the N400 amplitude. In conclusion, literal, metaphorical, and anomalous sentences produced different scalp distributions of neural activity implying different neural processes. Furthermore, modality along with the figurativeness of the sentences produced different mean N400 amplitudes. The neural differences due to modality are suggested to be related to the imageability of the sentences. As predicted, the figurativeness and modality of language affects the processing mechanisms within the brain.
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