Removing Input from Smell Reveals the Importance of Olfactory Input on the Sensing of Food Outside of Aroma

Food consumption is by its nature a crossmodal, multisensory experience. The combined inputs from our senses provide the perception of a “flavor”. Altering input from one sensory modality can change the perception from another. Previous research has shown that visual, auditory, olfactory, and somatosensory, as well as gustatory systems contribute to flavor. However, the vast majority of this work concerns adding input to one of the senses, where there is a lack of research into the effect of instead removing passive sensory input from one modality, on the other senses. The study was designed to address the effect of sensory blockade on taste response. Two experiments were performed with this in mind. The first recruited 47 participants rating the sweetness of different solutions when adding or subtracting sensory input. Sucrose, sucrose plus vanilla odor, sucrose plus red color, and sucrose plus both combined were tasted under four conditions: a control, with blindfold, with nose clip, and combined blindfold and nose clip conditions. The results found as expected that adding vanilla odor enhanced the sweetness of the sucrose solution, however a significant inhibitory effect of the nose clips was also plain on sweet taste response. This effect surprisingly did not require a sweet odorant in the sucrose solution; sucrose itself was less sweet without passive olfactory input. No significant effects of visual input were recorded, thus olfaction was focused on in the following test. In the second experiment we investigated olfactory blockade on the other 5 classical senses, to determine if effects observed were limited to links between taste and olfaction, or were more broadly experienced across the senses, and thus could perhaps be attributed to attention or information processing. 45 panelists tested the intensity of sensory stimuli with and without nose clips. Results demonstrated that sweet taste was again impaired by loss of olfactory input, as were umami and bitter (with trends also for sour and salty), chemesthetic stimuli, and of course, detection of aroma. The results of this study suggest a close relationship between olfactory and gustatory input, and that humans may be less able to separate input from the senses, supporting evidence of constant passive crossmodal interaction.