Orange-Sweet Aroma Reduces Stress During Numerical Tasks: A Physiological and Psychological Evaluation of Olfactory Cognition

Abstract: This study examines the stress-reducing effects of the aroma of Orange-Sweet essential oil (product name) from the perspective of olfactory cognition. The research is motivated by a significant social issue: stress can hinder individuals from working and disrupt their daily lives. This research aims to clarify, using aroma, whether aroma can reduce stress within this context. The experiment was conducted in two conditions: one with Orange-Sweet aroma at the perceptual threshold, and the other above the threshold. To evaluate the stress-reducing effects of the aroma in terms of olfactory cognition, we employed multiple physiological and psychological measures during stress induced by numerical tasks. Previous studies have failed to detect clear physiological changes associated with aroma factors. Therefore, we sought to explore the underlying mechanisms of aroma-induced stress reduction by introducing different physiological measures. The physiological measures included facial thermography and electroencephalography (EEG). The psychological measures included the short version of the Profile of Mood States 2 (POMS2), "Jikakusho Shirabe, " and a Likert-scale survey assessing scent preference and intensity. From the EEG data, it was found that the Orange-Sweet aroma, at a concentration above the perceptual threshold, increased brain activity during a numerical task, leading to a state of concentration. From the psychological measures, we found that a weak aroma at　the perceptual threshold level inhibited the decline in "Vigor-Activity" on the POMS 2 and reduced "discomfort" in the "Jikakusho Shirabe". These findings suggest that even a weak aroma at the perceptual threshold may exert positive psychological effects, while a stronger aroma above the perceptual threshold may increase brain activity indicating a state of concentration. We plan to further examine the relationship between olfactory cognition and stress reduction effects using everyday relaxing aromas such as coffee and igusa (soft rush), within the same evaluation framework.

Keywords: Aroma, Olfactory cognition, Subjective rating, Jikakusho shirabe, EEG, Facial thermography, POMS2

DOI: 10.54941/ahfe1006971

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