Influence of Odor Hedonics, Food-Relatedness, and Motivational State on Human Sniffing

Sniffing is part of an active exploratory process aimed at identifying and locating biologically salient stimuli. However, there are few data on those factors that determine the nature of the sniff—its magnitude, duration, or frequency. The study reported here was aimed at increasing our understanding of human sniffing behavior by examining sniff magnitude and duration to odorants that independently varied in both food-relatedness and pleasantness, under conditions of both hunger and satiety. In two sessions, 25 subjects sniffed odorants that they had previously identified as varying in pleasantness (unpleasant, neutral, pleasant) and as food-related or not, as well as odorant blanks. During one session, the subjects were in a state of relative hunger, while in the second session, they had recently eaten. Sniffs were monitored using the Sniff Magnitude Test (Frank et al. 2006. Arch Otolaryngol Head Neck Surg, 132, 532–36), which sampled the changes in air pressure produced by the sniff and calculated the magnitude and time course of pressure changes. Sniffs, whether to odorants or blanks, were significantly longer and had higher overall and peak amplitudes when the subjects were hungry. Longer sniffs and overall greater amplitude were also elicited by pleasant, than by either neutral or unpleasant, odorants. Whether an odorant was food-related or not had no impact on any measured sniff parameters. These data reinforce a view that sniffing in humans is, as has been shown in rats, a means of exploring the environment in response to increased motivation to consume.