Cross-modal correspondences between odours and speed

Human odour perception is more than a straightforward sensory experience. It involves multiple stages of processing during which the rich complexity of an olfactory cue is internalized and encoded into a more concrete smell representation. This representation has been shown to be associated with concepts within several other sensory modalities (e.g. visual: colour, hue; auditory: pitch, timbre). However, such cross-modal correspondences between odours and more abstract perceptual concepts like speed have not been investigated yet. This study assessed whether odour and imagined speed share cross-modal associations. Participants were asked to smell eight different odours and associate them with an intuitive speed rating on a scale of 1 to 9. They were further asked to rate the odours on three perceptual scales (intensity, sweetness, sourness). In order to control for mental imagery during this association, odours were assessed for recognition. The results indicate cross-modal associations between odour and the abstract concept of speed. Odour intensity, but not sweetness or sourness were also positively correlated with speed ratings. These associations held true even when controlling for accurate odour recognition. Investigating what role these cross-modal associations play for temporal perception has wide-reaching implications for the use of olfactory cues in human navigation systems.