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Abstract

For decades, visual hemifield (VHF) experiments have served as a behavioral window into hemispheric specialization. According to VHF studies of emotion in right-handers, the left hemisphere is specialized for positive and approach emotions, and the right hemisphere for negative and withdrawal emotions. VHF effects reverse in left-handers, suggesting a reversed hemispheric organization of emotion. However, recent studies reveal implicit associations between left-right space and emotional valence, calling these conclusions about hemispheric specialization into question. In right-handers, positive emotions are implicitly associated with the right side, the side on which they can act more fluently with their dominant hand, and negative emotions with the left side. In lefthanders, associations between space and valence are reversed. Since VHF studies rely on lateralized stimulus presentation, emotional VHF effects could arise due to fluency-based space-valence associations: not to hemispheric specialization. Here we tested competing accounts of emotional VHF effects by training natural right-handers to be transiently left-handed. Participants categorized faces presented in the right or left VHF as positive or negative. In Experiment 1, untrained right-handers tended to judge neutral faces presented on the right as positive and on the left as negative. Untrained left-handers showed the opposite pattern. In Experiment 2, changes in motor fluency induced changes in righthanders’ VHF effects. After motor training, right-handers categorized faces like natural left-handers. In light of these results, emotional VHF effects can no longer be interpreted as evidence for hemispheric specialization of emotions. Asymmetries in motor fluency can determine spacevalence associations and reverse emotional VHF effects.