PIXABAY, PUBLICDOMAINPICTURESIn 2014, Rockefeller University’s Leslie Vosshall and colleagues reported the results of an olfaction study in humans, concluding that people are able to discriminate at least one trillion different odors. That number smashed the old approximation by many orders of magnitude, and far surpassed the estimates for how many colors and tones humans can distinguish. Now, citing potential flaws in that analysis, an independent team is challenging the published figure.
“The first main concern is that the estimated number of discriminable stimuli depends steeply, systematically, and non-asymptotically on choices of arbitrary experimental parameters, among them the number of subjects enrolled, the number of discrimination tests performed, and the threshold for statistical significance,” Arizona State University’s Richard Gerkin and Bates College’s Jason Castro wrote in their study, published in eLife this week (July 7).
Gerkin and Castro picked through the Vosshall team’s methodology, finding that different statistical or experimental conditions would have yielded estimates of the number of detectable odor stimuli anywhere from 5,000 to 1029.
“We also point out that the conclusion in the 2014 paper relies heavily on untested assumptions about smell perception. And the equation used actually shows that the number of distinguishable ...
