You can see the color white; you can hear white noise. Now, Weizmann Institute researchers show that you can also smell a white odor. Their research findings appear today in the Proceedings of the National Academy of Sciences (PNAS).
The white we see is actually a mixture of light waves of different wavelengths. In a similar manner, the hum we call white noise is made of a combination of assorted sound frequencies. In either case, to be perceived as white, a stimulus must meet two conditions: The mix that produces them must span the range of our perception; and each component must be present at the exact same intensity. Could both of these conditions be met with odors, so as to produce a white smell? That question has remained unanswered, until now, in part due to such technical difficulties as getting the intensities of all the scents to be identical.
A research team in the Neurobiology Department, led by research student Tali Weiss and Dr. Kobi Snitz, both in the group of Prof. Noam Sobel, decided to take up the challenge. They began with 86 different pure scents (each made of a single type of odor molecule) spanning the entire "smell map," diluted them to obtain similar intensities and then created blends. Each blend contained a different mixture of odors from various parts of the smell map. These blends were then presented in pairs to volunteers, who were asked to compare the two scent-blends.
The team discovered that the more odors that were blended together in the paired mixtures, the more the subjects tended to rate them as similar – even though the two shared no common components. Blends that each contained 30 different odors or more were thought to be almost identical.
The researchers then created a number of such odor blends, giving them a nonsense name: Laurax. Once the subjects were exposed to one of the Laurax mixes and became accustomed to the smell, they were exposed to new blends – mixtures they had not previously smelled. They also called some of these new blends "Laurax," but only if those contained 30 or more odors and these encompassed the range of possible smells. In contrast, mixtures made of 20 scents or fewer were not referred to as Laurax. In other words, Laurax was a white smell. In a follow-up experiment, volunteers described it as being neutral – not pleasant, but not unpleasant.
"On the one hand," says Sobel, "The findings expand the concept of 'white' beyond the familiar sight and sound. On the other, they touch on the most basic principles underlying our sense of smell, and these raise some issues with the conventional wisdom on the subject." The most widely accepted view, for instance, describes the sense of smell as a sort of machine that detects odor molecules. But the Weizmann study implies that our smell systems perceive whole scents, rather than the individual odors they comprise.
Weizmann Institute of Science: http://www.weizmann.ac.il
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Algorithms developed by Google designed to encode thoughts, could lead to computers with ‘common sense’ within a decade, says leading AI scientist
New fossil evidence suggests dogs emerged as a separate species from wolves far earlier than scientists previously believed
Researchers discover the 425-million-year-old remains of a new species of parasite - still clamped to the host animal it invaded.
It should be raptor egg blue instead of robin egg blue. Some modern birds lay colourful eggs, but now we know it's a trick their dinosaur ancestors used too
WASHINGTON (Reuters) - Scientists on Thursday unveiled the most comprehensive analysis ever undertaken of the world's ocean plankton, the tiny organisms that serve as food for marine creatures such as the blue whale, but also provide half the oxygen we breathe.
Scientists on Thursday unveiled the most comprehensive analysis ever undertaken of the world's ocean plankton, the tiny organisms that serve as food for marine creatures such as the blue whale, but also provide half the oxygen we breathe.
Researchers say they're excited about a new brain implant that allowed a paralyzed patient to control a robotic arm with his mind. Erik Sorto is the first in the world to have this new neural prosthetic device. Elaine Quijano reports.
Genetically, at least, not that much has changed in the billion years since you two last shared a relative. Roughly half the 500 genes yeast need for life are interchangeable with the human versions.
What controls aging? Biochemist Cynthia Kenyon has found a genetic mutation that can more than double the lifespan of a tiny worm, which points to how we might one day significantly extend human life.
Java sparrows amp up their tunes with acoustic beak taps synchronized with chirps