Chemical Senses 6: 445-453,
© 1981
research-article |
Odor detection curves for n-pentanoic acid in dogs and humans*
1Department of Animal Biology, School of Veterinary Medicin Philadelphia, PA 19104, USA 2Clinical Smell and Taste Research Center, School of Medicine Philadelphia, PA 19104, USA 3Department of Physiology, School of Medicine, University of Pennsylvania Philadelphia, PA 19104, USA 4Veterans Administration Medical Center Philadelphia, PA 19104, USA
* Reprint requests to Dr.D.A.Marshall, Clinical Smell and Taste Research Center, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
The ability of dogs and humans to detect vapor concentrations of n-pentanoic (valeric) acid was measured under directly comparable testing conditions. The minimum concentrations detected by dogs were 3.3 x 106 molecules/cm3 by two German shepherds, and 8.8 x 108 molecules/cm3 by a Fox terrier. The average minimum detected by humans was 5 x 1010 molecules/cm3. Detection curves for the two best performing human subjects showed double reversals in slope (a "notch") at approximately one-half log10 unit of concentration above the minimum detectable level. Two distinct notches, separated by about 2 log10 units of concentration, occurred in the curves for the dogs; the lower notch, present in the curves of the two best performers, fell approximately 2 log10 units above the lowest minimum concentration detected. Performance differences producing these latter notches were statistically significant and, according to one interpretation, could reflect the availability of less primary stimulus information at the two concentrations where they occur, a possible result of three slightly different ranges of receptor sensitivity.