Effects of Scent Presentation on Choice and Judgment
Authors: Hatano Yusuke , Watanuki Keiichi , Kaede Kazunori 
Published: June 2022

In recent years, scents have been increasingly used in various situations as stimulants in addition to content, such as in 4DX movie screenings and as original aromas to enhance brand images. Research on scents has also garnered interest; a study conducted at a casino in Las Vegas reported that creating specific scents around the slot machines increased the input number of coins by approximately 45%, and research on the effects of lighting or scent have suggested that scents may influence purchase motivations. The olfactory brain that is responsible for the sense of smell overlaps with the emotional brain that is responsible for emotions and is believed to contribute greatly to its development. The sense of smell is considered to have stronger connections to emotions than the other senses, and there is growing interest in the use of scents to manipulate psychological states into desired states. We experimentally evaluated the relationships between emotional changes caused by scents and image evaluations. Further, we obtained the image evaluation impressions and quantified the influences of scent on selection and evaluation. In order to evaluate the differences in selection, we focused on the categories of images. We prepared five categories of images: sweets, fruits, flowers, nature, and indoor images, and asked the participants to select images that did not overlap the categories. An evaluation index was created based on the harmony of the fragrance with the impression of the image. The results showed that there was a positive correlation between the change in the selection rate and the harmony with the fragrance in each category. This suggests that the presentation of scents gives a better impression to images that have a high degree of harmony with scents. To assess the effects of emotion induction by scent presentation on evaluation of image impressions, we conducted experiments for image impression evaluations by presenting scents to 10 healthy male participants in their 20s (22.3±1.3 years) with no known olfactory abnormalities. The ambient air was scented using a bubbling method and supplied through a nasal cannula. We used peppermint essential oil, which has different pleasant and unpleasant emotion associations depending on participant experiences and presented it at a concentration of 1%. The Japanese version of the POMS2 (short version) assessments were used for subjective evaluations of emotion induction, and the emotion changes was evaluated from the differences in scores before and after the experiments. To objectively evaluate emotions, we used a measure the volumetric pulse waveforms from the participant fingertips as well as sweating characteristics. Subjective evaluations of the scent were conducted after completion of the impression evaluations for two items, namely "pleasant-unpleasant" and "arousing-sedating". Two pleasant images, one neutral image, and two unpleasant images were selected based on subjective emotional valences. In the impression evaluation experiment that focused on changes in emotions, a positive correlation was observed between changes in images and scent sensitivity evaluations for positive images, and a negative correlation was similarly identified for negative images.