If you have ever experienced eating delicious food while suffering from a strong flu, you must have noticed how the flavor of the meal is not the same as when we are not sick. No matter how beautiful and appetizing the dish is, we cannot savor that food with the same pleasure we have when we are well. In fact, there seems to be a lack of taste, doesn’t it? There is indeed an important relationship between smell and the gustatory system, such that the latter is impaired when our ability to sense odors is diminished. The interaction between these two senses is well known and easily perceived, but could odors alter other sensations, such as the perception of textures? What would be the relationship between touch and smell?
To answer this question, a study showed that smells can modify people's perception of the softness of fabric samples. During the study, volunteers were exposed to two different odors, lemon scent (classified as pleasant) and animal scent (unpleasant), and then had to evaluate the softness of the fabric samples solely through the touch of one hand. The result showed that, although the textures were the same, participants rated the samples as softer when presented with the lemon scent than when presented with the animal scent, demonstrating that smell can modify tactile perception.
Another study sought to evaluate whether the use of different fragrances in a shampoo could alter the perception of the texture of the product and hair (during and after washing) reported by participants. To conduct the work, researchers added various types of fragrances to the same shampoo base, so that the products differed exclusively by odor. Volunteers had to use each of the samples at home, at least once over three days, and then respond to an evaluation questionnaire. The experiment showed that despite the products being identical, the fact that they had different scents led to a change in the perception of the texture characteristics of both the shampoo and the hair, again showing the capacity for interaction between these senses.
In addition to highlighting the influence of smell on touch, what is interesting about the above study is that despite very different fragrances being chosen based on olfactory characteristics, all were pleasant and commercially used, suggesting that the changes generated by odors in the evaluation of a product are not solely due to them being pleasant or unpleasant, but that there are other mechanisms involved in this effect. This is yet another example that our perception is not formed by the senses in isolation, but by the interaction between them, as we saw in the post Perception: reconstructing the world.
Maria Cristina Valzachi is a pharmaceutical biochemist graduated from the Faculty of Pharmaceutical Sciences at USP and holds a master's degree in Pharmacology from the Institute of Biomedical Sciences at USP. Currently pursuing a doctorate at this same institution, she is dedicated to research and studies in the fields of Neurochemistry and Behavioral Pharmacology, with an emphasis on adolescence. She has a special interest in all fields related to education and the dissemination of ideas.
Contact: cris.valzachi@gmail.com
REFERENCES
Churchill A, Meyners M, Griffiths L, Bailey P. The cross-modal effect of fragrance in shampoo: modifying the perceived feel of both product and hair during and after washing. Food Quality and Preference. 2009;20:320-328;
Demateè ML, Sanabria D, Sugarman R, Spence C. Cross-modal interactions between olfaction and touch. Chem Senses. 2006;31:291-300.
Figure: http://commons.wikimedia.org/wiki/File:Girl_hair.JPG?uselang=pt-br
