Individual differences in thresholds and quality reports of human subjects to various odors

Abstract

Sixty-three subjects were selected on the basis of their relative ability (n = 30) or inability (n = 33) to detect the intense urine–sweaty odor of the diastereoisomeric ketone, cis-4-(4′-t-butylcyclohexyl)- 4-methyl-2-pentanone (pemenone). Absolute thresholds were determined, and quality reports and hedonic ratings were obtained for near-threshold concentrations of pemenone and five other odorous compounds. Several of these compounds were selected because large individual differences in sensitivity (specific anosmias) were known to exist. A principal compound analysis of threshold concentrations indicated that three orthogonal factors well described the relationships between sensitivities to the compounds. Threshold concentrations of pemenone and androstenone were highly correlated and the first factor was defined by relationships between those odorants and isovaleric acid, all modally putrid-smelling compounds. Subjects relatively osmic for pemenone generally reported a putrid odor for pemenone, but anosmics reported mostly other qualities. These relationships between relative sensitivity and the quality reports elicited by the different compounds are consistent with a multiple-profile model of odor quality perception. That model postulates that most odor molecules interact with more than one perceptual channel (receptor process) and that any individual alteration in the relative specificity or deletion in the number of such receptor processes could alter the pattern of interaction and thus should give rise to alterations in the quality or intensity of the resulting odor perception.