Although it is agreed that physicochemical features of molecules determine their perceived odor, the rules governing this relationship remain unknown. A significant obstacle to such understanding is the high dimensionality of features describing both percepts and molecules. We applied a statistical method to reduce dimensionality in both odor percepts and physicochemical descriptors for a large set of molecules. We found that the primary axis of perception was odor pleasantness, and critically, that the primary axis of physicochemical properties reflected the primary axis of olfactory perception. This allowed us to predict the pleasantness of novel molecules by their physicochemical properties alone. Olfactory perception is strongly shaped by experience and learning. However, our findings suggest that olfactory pleasantness is also partially innate, corresponding to a natural axis of maximal discriminability among biologically relevant molecules.
They used subjects from a variety of cultures with radically different cuisines. To some extent this should be totally predictable from cognitive psychology and evolutionary biology, but it is nice to be able to fill in a neuromolecular gap. This also puts in perspective the finding that there is variation in olfactory perception. This isn’t an either/or situation, general tendencies are bounded by deviation from the norm, and, the shape of the distribution likely varies by dimension (that is, some smells are likely less constrained by universal preferences and perceptions).