Left Hemisphere Dominance for Negative Facial Expressions: The Influence of Task.

E Darcy Burgund

doi:10.3389/fnhum.2021.742018

Abstract

Major theories of hemisphere asymmetries in facial expression processing predict right hemisphere dominance for negative facial expressions of disgust, fear, and sadness, however, some studies observe left hemisphere dominance for one or more of these expressions. Research suggests that tasks requiring the identification of six basic emotional facial expressions (angry, disgusted, fearful, happy, sad, and surprised) are more likely to produce left hemisphere involvement than tasks that do not require expression identification. The present research investigated this possibility in two experiments that presented six basic emotional facial expressions to the right or left hemisphere using a divided-visual field paradigm. In Experiment 1, participants identified emotional expressions by pushing a key corresponding to one of six labels. In Experiment 2, participants detected emotional expressions by pushing a key corresponding to whether an expression was emotional or not. In line with predictions, fearful facial expressions exhibited a left hemisphere advantage during the identification task but not during the detection task. In contrast to predictions, sad expressions exhibited a left hemisphere advantage during both identification and detection tasks. In addition, happy facial expressions exhibited a left hemisphere advantage during the detection task but not during the identification task. Only angry facial expressions exhibited a right hemisphere advantage, and this was only observed when data from both experiments were combined. Together, results highlight the influence of task demands on hemisphere asymmetries in facial expression processing and suggest a greater role for the left hemisphere in negative expressions than predicted by previous theories.

Highlights

Facial expression recognition is an important ability that provides crucial information about others’ internal states
The Valence Specific Hypothesis (VSH; e.g., Adolphs et al, 2001), Left Hemisphere Dominance for Negative Expressions in contrast, proposes that the right hemisphere is dominant for the processing of negative emotions but the left hemisphere is dominant for the processing of positive emotions
The finding of a left-hemisphere advantage for fearful and sad expressions contrasts with predictions made by the Right Hemisphere Hypothesis (RHH), VSH, and Approach/Withdraw Hypothesis (AWH), all of which predict a right hemisphere advantage

Summary

Introduction

Facial expression recognition is an important ability that provides crucial information about others’ internal states. The extent to which emotional facial expressions are differentially processed by areas within the right and left hemispheres of the brain is a topic of significant debate Much of this debate has focused on three theories of hemisphere asymmetries in emotion processing. A similar theory, the Approach/Withdraw Hypothesis (AWH; e.g., Harmon-Jones, 2004), argues that the right hemisphere is dominant for withdrawal emotions and the left hemisphere is dominant for approach emotions. The difference between this theory and the VSH is that it classifies anger as an approach (left hemisphere) emotion rather than a negative (right hemisphere) emotion

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Conclusion