Cross-modal impacts of olfactory perception and individual differences in emotional responses to odors modulate hedonic evaluations of visual scenes.

In line with the critical role of human olfaction in motivated behavior, positively valenced odors have been shown to boost hedonic perception of visual stimuli, especially facial expressions, compared to unpleasant smells. However, it remains unclear whether pleasant fragrances, which vary in character and subjective affective profile, differentially impact different categories of visual stimuli. We also postulate that individual differences in emotional responses to odors modulate their subsequent effect on hedonic evaluations of images. The current study investigated how (relative to a clean air control) 4 pleasant odors (vanilla, rose, lavender, and lemon) influenced hedonic ratings of different categories of visual images (faces, landscapes, and objects), with each category comprising images of neutral and positive valence. Forty participants (aged 18 to 35) rated the pleasantness of each image during each odor condition presented using a computer-controlled olfactometer. Participants also reported their emotional response to each fragrance on 7 dimensions (happiness, disgust, relaxation, thirstiness, sensuality, energy, and nostalgia) using the Liverpool Emotion and Odor Scale (LEOS), self-report questionnaire. Pleasant odors significantly affected image pleasantness ratings, but the effects of specific fragrances differed by image category. Individual differences in emotional experiences elicited by each fragrance were shown to modulate the impact of odors on hedonic evaluations, and these effects varies across the different image categories. The findings offer new insights into the differential effects of pleasant odors on hedonic evaluations of visual stimuli and the role of individual affective processing in cross-modal olfactory-visual integration.