Examining the Effect of Peppermint on Cognitive Functioning

COPYRIGHT 2014 BY PSI CHI, THE INTERNATIONAL HONOR SOCIETY IN PSYCHOLOGY (VOL. 19, NO. 3/ISSN 2164-8204) *Faculty mentor As the least studied of the five human senses, olfaction plays an important role in our perception of the world and has extensive, but often unnoticed, influence on our behaviors. Goldstein (2010) summarized the function of the olfactory system, saying that odorant molecules come into the nose and stimulate the receptor neurons in the olfactory mucosa, which send signals to the olfactory bulb. Neurons in the olfactory bulb then transmit signals to the priform cortex and the amygdala, and next to the orbitofrontal cortex. However, the neurons in the orbitofrontal cortex do not always respond in the same manner to a certain odorant molecule. Other factors such as expectation can alter the perception of odorants and neural processing to create olfactory illusions. Herz and von Clef (2001) first demonstrated that the perception of the hedonics of odorants could be significantly affected by the accompanying odor labels. In some cases, the perception of an odorant was inverted by the labels. For example, a 1:1 combination of isovaleric and butyric acid (rated as having a “cheesy” smell by a separate set of observers) was rated neutral when labeled parmesan cheese and was rated extremely unpleasant when labeled vomit. Morrot, Brochet, and Dubourdieu (2001) found that adding red coloring to white wine led wine tasters to describe the aroma with terms that were usually associated with red wine. Similarly, a test odorant consisting of a mixture of sweat and cheddar cheese was rated more pleasant when it was labeled cheddar cheese than when it was labeled body odor (de Araujo, Rolls, Velazco, Margot, & Cayeux, 2005). Herz (2003) took a further step. She asked participants to evaluate the pleasantness, safety, and familiarity of eight odorants based on the odorants only, or the odor labels only, or both. The results showed that the ratings of odor hedonics ABSTRACT. When odorant molecules enter the nose, they do more than create a sensation of smell. Previous research has documented the influence of odorants on mood, physiology, cognitive functioning, and behaviors. The current study investigated whether and how peppermint, an odor commonly described as alerting, and the expectation of its presence, would affect attention and working memory. Fifty female undergraduate students were randomly assigned to one of three conditions: peppermint (threshold odorant, no expectation), expectation (no odorant, expectation), and control (no odorant, no expectation). Participants completed the Stroop Color-Word Interference Test and memory span assessments while wearing facial masks that either had the odorant applied to them or had no odorant applied in accordance with their condition assignments. We found no significant differences in performance on the Stroop Test and the memory span as ses sments across a l l three condi t ions . We propose that peppermint odorants of higher concentration may be needed to produce enhancing effects on cognitive functioning. The current study contributed to the literature as a pilot study on the topic and posed questions for future researchers. Examining the Effect of Peppermint on Cognitive Functioning