Valence-specific laterality effects in vocal emotion: interactions with stimulus type, blocking and sex.

Valence-specific laterality effects have been frequently obtained in facial emotion perception but not in vocal emotion perception. We report a dichotic listening study further examining whether valence-specific laterality effects generalise to vocal emotions. Based on previous literature, we tested whether valence-specific laterality effects were dependent on blocked presentation of the emotion conditions, on the naturalness of the emotional stimuli, or on listener sex. We presented happy and sad sentences, paired with neutral counterparts, dichotically in an emotion localisation task, with vocal stimuli being preceded by verbal labels indicating target emotions. The measure was accuracy. When stimuli of the same emotion were presented as a block, a valence-specific laterality effect was demonstrated, but only in original stimuli and not morphed stimuli. There was a separate interaction with listener sex. We interpret our findings as suggesting that the valence-specific laterality hypothesis is supported only in certain circumstances. We discuss modulating factors, and we consider whether the mechanisms underlying those factors may be attentional or experiential in nature.