Multisensory Tuning of Emotional Face Recognition: A Comparative Study of Olfactory and Gustatory Influences

Olfaction and gustation are central to affective experience, yet their distinct contributions to social emotion perception remain underexplored compared to vision and audition. This study examined how sweet and sour chemosensory cues modulate emotional judgments of facial expressions, testing whether judgments are systematically biased toward hedonically congruent emotion categories. Two behavioral experiments were conducted. In the olfactory session, participants categorized happy, disgusted, and neutral faces at high (100%) and low (50%) intensity while exposed to either a sweet (melon) or sour (vinegar) odor. In the gustatory session, they performed the same task after ingesting the sweet (sucrose) or sour (citric acid) solution. Accuracy and reaction times were analyzed using generalized linear mixed models. The analyses of accuracy data revealed a significant main effect of intensity and a significant condition × emotion interaction. Happy faces were more accurately identified in the sweet condition, whereas disgusted faces were more accurately identified in the sour condition. Sweet and sour chemosensory cues systematically bias emotional judgments of visual facial expressions. These effects support hedonic congruency predictions and highlight the importance of incorporating chemosensory context into multisensory models of emotion.