Naturalness is more than a marketing trend. Neuroscientific studies brought evidence of distinct cognitive and cerebral processing of naturally occurring objects vs. human-made objects. However, these studies have focused on the visual modality and little knowledge is available concerning olfaction. If smells do not seem less capable of evoking nature, we wonder whether naturalness would share the same meaning between the visual and olfactory domains. Images have been considered natural when representing natural objects. Thus, one assumption that may be made is that, as for images, the naturalness of a smell would rely on what that smell evokes (i.e. a naturally occurring or a human made entity).
Following this hypothesis, we set up an Implicit Association Task testing for association between odors and images representing natural or human-made objects. In this task, 34 French participants were asked to categorize as fast as possible images and smells into one of four categories: fruit or candy for smells, mountains or building for images. It was expected that participants would be faster in congruent condition, i.e. when associated concepts (e.g. natural smells and natural images) shared the same respond key, compared to incongruent condition, i.e. when dissociated concepts (e.g. natural smells and artificial images) shared the same respond key. We ran a linear mixed model with reaction time (RT) as dependent variable, participants and stimuli as random factors, and conditions (congruent vs. incongruent), modality (images vs. odors) and their interaction as fixed effects. Results showed a significant effect of conditions, RT being lower in congruent condition, and of modality, RT being lower for images. These results suggest that smells and images are associated based on the naturalness of the object they represent.
This research was funded by Mane Company, and hosted by the research center of the Institute Paul Bocuse and by Lyon Neurosciences Research Center.