Investigating Emotional Lateralization Biases with Verbal and Nonverbal Stimuli

Poster Session A - Saturday, April 13, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Grace Wang^1,2, Jed Meltzer^1,2; ¹University of Toronto, ²Rotman Research Institute at Baycrest

The treatment of mood disorders has been informed by a theoretical division of labour between the brain hemispheres in processing emotions. However, lateralization of emotional function remains unclear, with two major competing theories emerging. The Right Hemisphere Hypothesis proposes that emotional perception and expressions are primarily processed by the right hemisphere, whereas the Valence Hypothesis suggests that positive emotions are processed in left brain regions and negative emotions in the right. Although studies have come forward in support of either theory, the degree of lateralization becomes more complex when emotional stimuli engage with functions lateralized across hemispheres, such as language and face perception. The current study addresses the cognitive processing of emotional information across the two hemispheres, specifically examining the competing hypotheses by using different stimuli types to compare differences in hemispheric performance. Our online study employed the divided visual field paradigm and two valence judgment tasks with words and faces. We observed left hemisphere dominance in word processing, but no significant lateralization for face stimuli. Although there was increased accuracy for negative words and for positive faces, there were no interaction effects between visual field and valence, thus no support for either hypothesis of emotional lateralization. The observed asymmetry in the neural control of emotion may be a product of asymmetrical control of these functional lateralization biases for specific stimulus modalities. An improved understanding of hemispheric interactions when processing emotional stimuli can elucidate and inform the effectiveness of the treatment of mood disorders using non-invasive brain stimulation.

Topic Area: EMOTION & SOCIAL: Emotion-cognition interactions