Semi-Daily Journal Archive

The Blogspot archive of the weblog of J. Bradford DeLong, Professor of Economics and Chair of the PEIS major at U.C. Berkeley, a Research Associate of the National Bureau of Economic Research, and former Deputy Assistant Secretary of the U.S. Treasury.

Sunday, December 17, 2006

Scent Trails

But you would need a much longer neck to follow scent trails at speed:

3quarksdaily: A team of neuroscientists and engineers, led by Noam Sobel of the University of California, Berkeley, and the Weizmann Institute of Science in Rehovot, Israel, decided to test this conventional wisdom.

The team first laid down a 10-metre-long trail of chocolate essential oil in a grass field (the scent was detectable but not strong or overpowering). Then they enlisted 32 Berkeley undergraduates, blindfolded them, blocked their ears and set them loose in the field to try to track the scent. Each student got three chances to track the scent in ten minutes; two-thirds of the subjects finished the task. And when four students practiced the task over three days, they got better at it.

Next, the team tested how the students were following the trails. They counted how many whiffs of air each student took while tracking the scent trail, and tested the effect of blocking one nostril at a time. The scientists found that humans act much like dogs do while tracking a scent, sniffing repeatedly to trace the smell's source. They didn't do so well with one blocked nostril, suggesting that the stereo effect of two nostrils helps people to locate odours in space...

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