Crossmodal correspondences between odors and contingent features: odors, musical notes, and geometrical shapes

Olfactory experiences represent a domain that is particularly rich in crossmodal associations. Whereas associations between odors and tastes, or other properties of their typical sources such as color or temperature, can be straightforwardly explained by associative learning, other matchings are much harder to explain in these terms, yet surprisingly are shared across individuals: The majority of people, for instance, associate certain odors and auditory features, such as pitch (Belkin, Martin, Kemp, & Gilbert, Psychological Science 8:340–342, 1997; Crisinel & Spence, Chemical Senses 37:151–158, 2012b) or geometrical shapes (Hanson-Vaux, Crisinel, & Spence, Chemical Senses 38:161–166, 2013; Seo, Arshamian, et al., Neuroscience Letters 478:175–178, 2010). If certain odors might indeed have been encountered while listening to certain pieces of music or seeing certain geometrical shapes, these encounters are very unlikely to have been statistically more relevant than others; for this reason, associative learning from regular exposure is ruled out, and thus alternative explanations in terms of metaphorical mappings are usually defended. Here we argue that these associations are not primarily conceptual or linguistic, but are grounded in structural perceptual or neurological determinants. These cases of crossmodal correspondences established between contingent environmental features can be explained as amodal, indirect, and transitive mappings across modalities. Surprising associations between odors and contingent sensory features can be investigated as genuine cases of crossmodal correspondences, akin to other widespread cases of functional correspondences that hold, for instance, between auditory and visual features, and can help reveal the structural determinants weighing on the acquisition of these crossmodal associations.     

As bitter as a trombone: synesthetic correspondences in nonsynesthetes between tastes/flavors and musical notes

In parallel to studies of various cases of synesthesia, many cross-modal correspondences have also been documented in nonsynesthetes. Among these correspondences, implicit associations between taste and pitch have been reported recently (Crisinel & Spence, 2009, 2010). Here, we replicate and extend these findings through explicit matching of sounds of varying pitch to a range of tastes/flavors. In addition, participants in the experiment reported here also chose the type of musical instrument most appropriate for each taste/flavor. The association of sweet and sour tastes to high-pitched notes was confirmed. By contrast, umami and bitter tastes were preferentially matched to low-pitched notes. Flavors did not display such strong pitch associations. The choice of musical instrument seems to have been driven primarily by a matching of the hedonic value and familiarity of the two types of stimuli. Our results raise important questions about our representation of tastes and flavors and could also lead to applications in the marketing of food products.     

Crossmodal associations between flavoured milk solutions and musical notes

A number of crossmodal associations have now been described in the context of food evaluation, such as between tastes or flavours and musical notes (Crisinel & Spence, 2010b). Here we extend these findings by presenting flavoured milk solutions of varying fat contents. The participants in the present study matched a series of milk samples to musical notes. They chose both the pitch and the class of instrument that they felt was most appropriate for each sample. Participants also rated various features of the samples, such as their pleasantness, bitterness, or familiarity. Consistent associations between flavours and both pitch and instruments were confirmed. However, fat content did not influence either the pitch or instrument chosen, although it did have an effect on pleasantness and intensity ratings. These results demonstrate that flavour–sound associations are not restricted to basic tastes and flavours presented individually, but are still present in the context of more complex food stimuli. The present study opens the way for further investigations into the nature and characteristics of crossmodal associations (or correspondences) between more complex stimuli, both in the auditory and gustatory/olfactory modalities. This novel approach could lead to new insights into the representation of chemosensory stimuli in humans.