What the color white smells like

White is everywhere. We can see it (the background of this web page). We can hear it (white noise). And now for the first time ever, thanks to the efforts of a group of scientists, we may be able to smell it.

Huh? To grasp this concept, it's important to understand that whiteness, whether visual or aural, is the result of combining different elements that, in a sense, cancel each other out. White is "a combination of signals at equal intensity across a perceptual space," says Christina Agapakis at Scientific American. That's why you can use a prism to split white light into different colors, and why the steady hum of white noise carries every frequency humans are capable of hearing. But can the same principle be applied to smell, asked researchers in the neurobiology department of Israel's Weizmann Institute of Science.

For this experiment, researchers began with molecules of 86 different "pure" scents from across the entire "smell map," ranging from "fruity" to "decayed" to hard-to-categorize scents. Researchers combined these odors in various combinations to create a series of scent blends. They then presented these to volunteers, two blends at a time, and asked the participants to evaluate the sets.

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The team discovered that the more odors they jammed into the scent blends, the more likely testers were to rate the sets as smelling similar, even if the individual components of each blend were taken from completely different areas of the smell map. Researchers continued combining scents until they reached something called "olfactory white" — a smell that was just neutral, neither pleasant nor unpleasant.

"The findings expand the concept of 'white' beyond the familiar sight and sound," says researcher Noam Sobel. The research also challenges the widely held view that our sense of smell is a machine that detects individual odor molecules. Instead, these findings suggest that our complex smell systems take in whole scents at a time.

But then again, we don't initially "see" pictures or "hear" song arrangements in terms of their individual components. Your brain is wired to experience the whole thing first.