A new paper out of Noam Sobel’s lab at the Weizmann Institute has been getting a lot of media play. The piece by Stephanie Pappas at LiveScience (“Olfactory White: Newly Discovered Odor Is Blend Of Smelly Compounds”) is lame, and misleadingly titled. The one from Sid Perkins at ScienceNow is better and includes this fairly restrained quote:
“Olfactory white is a neat idea, and it draws interesting parallels to white light and white noise,” says Jay Gottfried, an olfactory neuroscientist at Northwestern University’s Feinberg School o, f Medicine in Chicago, Illinois. The new study “definitely adds new information about how the brain interprets odors,” he notes.Sobel’s team selected a bunch of smells that cover odor space (defined by sensory and physiochemical means) and diluted them to smell (roughly) equally intense. Then they randomly combined the odors into mixtures with varying numbers of components. By the time the mixtures reached around 30 components, they all began to smell about the same. To the extent this is remarkable it is because the 30-component mixtures had no components in common. (In contrast, a combo of 30 floral notes would be easily distinguishable from a combo of 30 resinous notes.)
Sobel et al. go to some lengths to experimentally demonstrate that these large mixtures, like large mixtures in tonal audition and color vision, converge on a perception that is, in technical psychophysical terms, “white.”
Well, the Weizmann Institute is trying to patent “a wide range of potential applications for olfactory white.” I have no doubt there are some clever applications, but my hunch is that each of them will prove to be quite narrowly focused.
Meanwhile, “olfactory white” may be rare or even nonexistent in the natural world, but I bet thousands of people smell it on a daily basis. Isn’t it the smell of any sizeable fragrance blending facility? I’ve been in a dozen of them and they all smell the same—it’s an unmistakable scent, yet not really of one thing or another. (Sure, some days a particular project will dominant the air. I’m talking about the ongoing background scent in the perfume labs and compounding rooms.)
Olfactory white: a “neat idea”? Yes. A “new smell”? Not so much.
The study discussed here is “Perceptual convergence of multi-component mixtures in olfaction implies an olfactory white,” by Tali Weissa, Kobi Snitza, Adi Yablonkaa, Rehan M. Khana, Danyel Gafsoub, Elad Schneidmana, & Noam Sobel, published online November 19, 2012 in Proceedings of the National Academy of Sciences USA.