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Electrophysiological Evidence for Hemispheric Coordination during Reading Emotion
Poster C24 in Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 4
I-Ling Hsu1, Chia-Lin Lee1,2,3,4; 1Graduate Institute of Linguistics, National Taiwan University, 2Department of Psychology, NTU, Taiwan, 3Graduate Institute of Brain and Mind Sciences, NTU, Taiwan, 4Neurobiology and Cognitive Science Center, NTU, Taiwan
Emotion is highly contextualized. During reading, emotional responses are co-constituted by lexical items and the preceding context. In particular, beyond the immediate attention allocation and emotional responses prompted by the emotionality of the words themselves (as indexed by enhanced P200 and Late Positive Potential (LPP) responses), linguistic emotional context triggers additional attention and evaluative processes for the perceived words (indexed by overall positive responses starting from the N400 time window and continuing to the LPP time window). However, how different brain resources collaborate to achieve these emotional responses is not well understood. Prior literature has shown that while both cerebral hemispheres are involved in processing emotion, the left hemisphere (LH) plays a dominant role in efficiently extracting gist from sentence context to modulate subsequent lexical processing. This raises an empirical question of how context-driven emotional responses during reading emerge across the two hemispheres. To address this, our study manipulated the emotionality of the context and the sentence-final target word, yielding four sentence types: (1) emotional contexts ending with emotion words, (2) emotional contexts ending with neutral words, (3) neutral contexts ending with emotion words, and (4) neutral contexts ending with neutral words. The sentence contexts were displayed word by word at the center of the screen, while the sentence-final words were shown either to the right visual field (RVF) or the left visual field (LVF), and were preferentially processed by the contralateral hemisphere. Participants silently read these sentences and made a valence judgment at the end of each sentence. Event-related potentials (ERPs) were obtained from 28 young native speakers of Taiwan Mandarin in Taipei, Taiwan (14 males; mean age 23.3 years, range: 20–29 years). ERP results showed that, following a neutral context, emotional sentence-final words elicited more positive responses during the P200 time window (100–300 ms) and LPP time window (600–900 ms) when presented to the LVF, but not the RVF. By contrast, within emotional contexts, while words elicited overall more positive responses regardless of VF presentation, the effect was longer-lasting when presented to the RVF. In addition, behavioral valence judgment results showed that while both emotional context and emotional ending words contributed to higher valence endorsement with both VF presentations, the overall valence endorsement rate was higher with RVF presentation. Overall, these findings highlight the joint contribution of both hemispheres and their coordination in processing emotions during reading. While both hemispheres are involved in appreciating the overall emotional message, our results suggest an RH advantage in processing the emotionality of individual lexical items and an LH advantage in evaluating the emotional context.
Topic Areas: Reading, Control, Selection, and Executive Processes