Researchers discover generic 'white' odor Laurax
(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. White noise 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 phenomenon 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 odor, 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 mixtures 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 volunteers 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
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.
Journal reference: Proceedings of the National Academy of Sciences
© 2012 Medical Xpress
- Wake up and smell the sweat Nov 21, 2007 | not rated yet | 0
- How Odors are sensed: A complex system clarified Apr 12, 2006 | not rated yet | 0
- Human ability good in tracking odors Aug 29, 2005 | not rated yet | 0
- Study shows people can guess personality via body odor Dec 05, 2011 | not rated yet | 0
- Initial research into 'Proust Phenomenon' reveals link between memories and smells Jan 30, 2012 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Why is zone 1 in liver more prone to ischemic injury?
10 hours ago Hi, Is it because around central vein, there is only deoxygenated blood from the vein where as in the periphery there is hepatic artery. Also why...
How can there be villous adenoma in colon, if there are no villi there
May 22, 2013 As title suggest. Thanks :smile:
How can there be a term called "intestinal metaplasia" of stomach
May 21, 2013 Hello everyone, Ok Stomach's normal epithelium is simple columnar, now in intestinal type of adenocarcinoma of stomach it undergoes "intestinal...
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013 From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
May 17, 2013 I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
- More from Physics Forums - Medical Sciences
More news stories
A brief visual task can predict IQ, according to a new study. This surprisingly simple exercise measures the brain's unconscious ability to filter out visual movement. The study shows that individuals whose ...
Psychology & Psychiatry 2 hours ago | 4.8 / 5 (4) | 0 |
Nervous about that upcoming job interview? You might want to take steps to reduce your jitters, especially if you are a man.
Psychology & Psychiatry 3 hours ago | 5 / 5 (1) | 0
(Medical Xpress)—Research by U of T Mississauga psychology professor Glenn Schellenberg reveals that two key personality traits – openness-to-experience and conscientiousness—predict better than IQ ...
Psychology & Psychiatry 5 hours ago | 5 / 5 (1) | 0 |
Parents naturally are concerned for their children's safety, particularly when there is news of a child abduction that happens close to home. Finding the balance between emotions and the "teachable moment" as parents talk ...
Psychology & Psychiatry 5 hours ago | not rated yet | 0
A new report on suicide in Ireland shows that suicide cases experienced a significant number (and intensity) of life events in the 6 months prior to their death.
Psychology & Psychiatry 5 hours ago | not rated yet | 0
Little is known about why asthma develops, how it constricts the airway or why response to treatments varies between patients. Now, a team of researchers at Weill Cornell Medical College, Columbia University Medical Center ...
47 minutes ago | not rated yet | 0 |
Scientists at the National Institutes of Health report they have discovered in mouse studies that a small molecule released in the spinal cord triggers a process that is later experienced in the brain as the sensation of ...
22 minutes ago | 5 / 5 (1) | 0 |
Teams of highly respected Alzheimer's researchers failed to replicate what appeared to be breakthrough results for the treatment of this brain disease when they were published last year in the journal Science.
22 minutes ago | not rated yet | 0 |
(Medical Xpress)—The human brain is able to identify individuals' voices by comparing them against an internal 'average voice' prototype, according to neuroscientists.
38 minutes ago | not rated yet | 0 |
An anti-cancer drug reverses memory deficits in an Alzheimer's disease mouse model, University of Pittsburgh Graduate School of Public Health researchers confirm in the journal Science.
15 minutes ago | not rated yet | 0 |
Since the discovery of Prontosil in 1932, sulfonamide antibiotics have been used to combat a wide spectrum of bacterial infections, from acne to chlamydia and pneumonia. However, their side effects can include serious neurological ...
22 minutes ago | not rated yet | 0 |