Researchers discover generic 'white' odor Laurax

by Bob Yirka report

(Medical Xpress)—Researchers working at the Weizmann Institute of Science in Israel have discovered that there exists an odor analog of the color white and the sound of white noise. They've been conducting studies on the odor, which they've named Laurax and have published a paper in the Proceedings of the National Academy of Sciences describing their results.

Most people are aware of white noise and the color white – both come about from the blending of many ingredients. is what people hear when multiple tones are played at once. Similarly, the color white comes about when multiple wavelengths converge. The research team in Israel wanted to know if there is a similar with odors so the set up a series of experiments to find out.

First, they concocted 86 odorants that represented the known olfactory spectrum in such a way as to make them all equally intense. From those they took small samples and mixed them together to create a variety of odor samples, with amounts of each of the basic odorants varying from 1 to 43. They then presented the samples to a group of 59 volunteers who were asked to rate pairs of the samples as to how close they smelled to one another.

In analyzing the results, the researchers found that as the number of odorants in each sample increased, the more difficulty the volunteers had in telling the difference between them. As the number approached 30, they found that most couldn't tell the difference at all, even if none of the odorants were the same. In addition, the odor that arose at such levels became distinct itself, which the researchers named, Laurax.

To learn more about the new generic , the team conducted another experiment where they asked volunteers to sniff one of four samples of Laurax over a period of three days to familiarize them with it. On the fourth day they were asked to sniff four and label them as Laurax or three other names that had been invented for the experiment. The researchers found that the volunteers were more likely to label a sample as Laurax if it had a high number of odorants in it, and as the odorants approached 30, most were inclined to give it that generic label. The researchers also found that most of the could tell the difference between different mixes of Laurax, similar to the way most can distinguish different shades of white.

More information: Weiss, T. et al., Perceptual convergence of multi-component mixtures in olfaction implies an olfactory white. Proceedings of the National Academy of Sciences, November 19, 2012. DOI: 10.1073/pnas.1208110109

Abstract
In vision, two mixtures, each containing an independent set of many different wavelengths, may produce a common color percept termed "white." In audition, two mixtures, each containing an independent set of many different frequencies, may produce a common perceptual hum termed "white noise." Visual and auditory whites emerge upon two conditions: when the mixture components span stimulus space, and when they are of equal intensity. We hypothesized that if we apply these same conditions to odorant mixtures, "whiteness" may emerge in olfaction as well. We selected 86 molecules that span olfactory stimulus space and individually diluted them to a point of about equal intensity. We then prepared various odorant mixtures, each containing various numbers of molecular components, and asked human participants to rate the perceptual similarity of such mixture pairs. We found that as we increased the number of nonoverlapping, equal-intensity components in odorant mixtures, the mixtures became more similar to each other, despite not having a single component in common. With ∼30 components, most mixtures smelled alike. After participants were acquainted with a novel, arbitrarily named mixture of ∼30 equal-intensity components, they later applied this name more readily to other novel mixtures of ∼30 equal-intensity components spanning stimulus space, but not to mixtures containing fewer components or to mixtures that did not span stimulus space. We conclude that a common olfactory percept, "olfactory white," is associated with mixtures of ∼30 or more equal-intensity components that span stimulus space, implying that olfactory representations are of features of molecules rather than of molecular identity.

Press release

Related Stories

Wake up and smell the sweat

Nov 21, 2007

Some people are oblivious to the odor in the locker room after a game, while others wrinkle their noses at the slightest whiff of sweat. Research by Prof. Doron Lancet and research student Idan Menashe of the Molecular Genetics ...

How Odors are sensed: A complex system clarified

Apr 12, 2006

Yale scientists have systematically plotted the responses of the entire Drosophila (fruit fly) olfactory system, providing the first multi-dimensional map of the range of odorants sensed and the regions of ...

Human ability good in tracking odors

Aug 29, 2005

University of California-Berkeley scientists say although humans may never match a dog's tracking ability, we apparently can sniff out and locate odors.

Study shows people can guess personality via body odor

Dec 05, 2011

(Medical Xpress) -- An interesting study conducted by Polish researchers Agnieszka Sorokowska, Piotr Sorokowski and Andrzej Szmajke, of the University of Wroclaw, has found that people are able to guess a person’s type ...

Recommended for you

Poor mother-baby bonding passed to next generation

27 minutes ago

Trust pathways in the brain are set in infancy and passed on from mother to child, according to landmark UNSW-led research. The work relates to oxytocin levels in new mothers and proves for the first time ...

Lift weights, improve your memory

19 hours ago

Here's another reason why it's a good idea to hit the gym: it can improve memory. A new Georgia Institute of Technology study shows that an intense workout of as little as 20 minutes can enhance episodic ...

Fat chats: The good, the bad and the ugly comments

21 hours ago

Cyberbullying and hurtful 'fat jokes' are disturbingly prevalent in the social media environment, especially on Twitter, says Wen-ying Sylvia Chou of the National Institutes of Health in the US. Chou is lead ...

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

alfie_null
not rated yet Nov 21, 2012
If I were subjected to an intense white odor, would I become desensitized to odors in general? Maybe this could become the ultimate room deodorizer.