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

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.