title: Humans can discriminate more than 1 trillion olfactory stimuli.
abstract: Humans can discriminate several million different colors and almost half a million different tones, but the number of discriminable olfactory stimuli remains unknown. The lay and scientific literature typically claims that humans can discriminate 10,000 odors, but this number has never been empirically validated. We determined the resolution of the human sense of smell by testing the capacity of humans to discriminate odor mixtures with varying numbers of shared components. On the basis of the results of psychophysical testing, we calculated that humans can discriminate at least 1 trillion olfactory stimuli. This is far more than previous estimates of distinguishable olfactory stimuli. It demonstrates that the human olfactory system, with its hundreds of different olfactory receptors, far outperforms the other senses in the number of physically different stimuli it can discriminate.
authors.affiliation: Laboratory of Neurogenetics and Behavior, The Rockefeller University, 1230 York Avenue, Box 63, New York, NY 10065, USA.
authors.forename: C
authors.initials: C
authors.lastname: Bushdid
authors.forename: M O
authors.initials: MO
authors.lastname: Magnasco
authors.forename: L B
authors.initials: LB
authors.lastname: Vosshall
authors.forename: A
authors.initials: A
authors.lastname: Keller
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009812:Odorants; D055696:Olfactory Perception; D012903:Smell / Q000502:physiology*; D055815:Young Adult