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Why Does Success Smell Sweet in Rehovot?
"A rose is a rose is a rose, but what makes some smells alluring and others disgusting? Is there something in a substance's chemistry that can predict how we will like its smell? Now scientists at the Weizmann Institute in Rehovot and the University of California at Berkeley have found that the pleasantness of an odor can indeed be predicted from its molecular structure.
Until now, there was no known physical factor that could explain how our brains sense odors. The new study, led by Prof. Noam Sobel of the institute's neurobiology department, constitutes a first step in understanding the physical laws that underlie smell. Their research was published in the Journal of Neuroscience.
To identify the general principles by which our sense of smell is organized, the researchers started with a database of 160 odors that had been ranked by 150 perfume experts according to a set of 146 characteristics (such as sweetish, smoky and musty). These data were then analyzed with a statistical program that examined the variances in perception. The scientists found that the data fell along an axis they called the "pleasantness rating" of the odors - running from "sweet" and "flowery" at one end to "rancid" and "sickening" at the other. The same distribution along this axis, they discovered to their surprise, closely describes the variation in chemical and physical properties from one substance to another. The researchers theorized that they could build a model to predict, from the molecular structure of a substance, how its smell would be perceived.
To doublecheck, Sobel and his team tested how experimental subjects assessed 50 odors they had never smelled before. They found that the ratings fit closely with the ranking shown by their model. In other words, they were able to predict the level of pleasantness quite well, even for unfamiliar smells. They noted that, although such preferences are commonly supposed to be culturally learned, the responses of Americans, Israeli Jews and and Israeli Arabs all fit the predictions."
Source: Judy Siegel-Itzkovich. New Worlds: Why does success smell sweet? JPost.com (29 Sep 2007) [FullText]
Until now, there was no known physical factor that could explain how our brains sense odors. The new study, led by Prof. Noam Sobel of the institute's neurobiology department, constitutes a first step in understanding the physical laws that underlie smell. Their research was published in the Journal of Neuroscience.
To identify the general principles by which our sense of smell is organized, the researchers started with a database of 160 odors that had been ranked by 150 perfume experts according to a set of 146 characteristics (such as sweetish, smoky and musty). These data were then analyzed with a statistical program that examined the variances in perception. The scientists found that the data fell along an axis they called the "pleasantness rating" of the odors - running from "sweet" and "flowery" at one end to "rancid" and "sickening" at the other. The same distribution along this axis, they discovered to their surprise, closely describes the variation in chemical and physical properties from one substance to another. The researchers theorized that they could build a model to predict, from the molecular structure of a substance, how its smell would be perceived.
To doublecheck, Sobel and his team tested how experimental subjects assessed 50 odors they had never smelled before. They found that the ratings fit closely with the ranking shown by their model. In other words, they were able to predict the level of pleasantness quite well, even for unfamiliar smells. They noted that, although such preferences are commonly supposed to be culturally learned, the responses of Americans, Israeli Jews and and Israeli Arabs all fit the predictions."
Source: Judy Siegel-Itzkovich. New Worlds: Why does success smell sweet? JPost.com (29 Sep 2007) [FullText]
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