Occurrence of habituation during repeated food exposure via the olfactory and gustatory systems

Abstract

Background: Greater exposure to an orosensory cue could increase habituation rate. This investigation examined salivary habituation during 10 lemon juice trials providing exposure via olfactory, gustatory, and combined systems.

Methods: Healthy, normal-weight, unrestrained females (age = 20.7 ± 2.7 year, body mass index [BMI] = 22.2 ± 1.5 kg/m(2), 70.0% white) were randomly assigned to 1 of 3 conditions: olfactory (SMELL: n = 8), gustatory (TASTE: n = 10), or olfactory+gustatory (SMELL+TASTE: n = 9). All conditions completed 12, 2-minute, trials (trials 1-2: water [baseline]; trials 3-12: lemon juice), in which salivation was measured. In conditions with taste exposure, 0.05 ml of the stimulus was placed on the tongue. In conditions with smell exposure, 4.0 g of the stimulus was held 0.5 in from the nose. Salivation was measured using dental rolls and mean salivation of every two trials was the dependent variable.

Results: A mixed-factor ANCOVA, controlling for baseline differences between the conditions in lemon juice hedonics, found a significant (p < 0.05) interaction of condition x trial. SMELL+TASTE significantly (p < 0.05) increased salivation from baseline to lemon juice exposure, and decreased salivation by the last two mean trials. TASTE had a significant (p < 0.05) increase in salivation from baseline to lemon juice, with no decrease.

Conclusion: Repeated exposure to an orosensory cue by combined olfactory and gustatory systems produced a faster habituation rate than exposure by the gustatory system alone. Thus, food cues that combine exposure to the olfactory and gustatory systems may enhance satiation.

Keywords: Consummatory; Gustatory; Habituation; Olfactory; Salivation; Satiation.