There is no doubt that odor is also an important factor to evaluate indoor air quality. Since the olfactory system was proven to be closely related to the limbic structures which support emotion, long-term memory and motivation, the psychological and the physiological effects of the essential oils have been widely researched in various fields. The odor environment formed by essential oils is popularly used in commercial facilities to make customers have special mood. On the other hand, there are also some studies about its effects on workplace productivity or learning performance in actual spaces such as office buildings and schools.
The purpose of this research is to examine whether the odor environment with essential oils has positive effects on learning performance in classroom and how students feel about the environment. In this paper, the influences of "rosemary" essential oil on learning performance and mood in healthy participants are tested. Participants were all graduate or undergraduate students and were divided into two groups randomly and assigned to conditions of rosemary aroma or no aroma (control).
Learning performance was assessed using two methods, and one is reading task and the other is verbal memory task. The number of letters participants read during the specified time and a percentage of correct answers of the comprehension test were used to evaluate the performance in reading task. For verbal memory task, Esperanto words were adopted. In order to assess memory retention, these tests were conducted again about one month after the first task unexpectedly for the same participants. Additionally, the subjective evaluations were done by participants before and after tasks with several mood scales: intensity of odor, hedonic scale, preference, acceptability of odor environment, evaluation of impression on odor and impression of experimental room.
As a result, under the condition of rosemary aroma, the number of letters in reading task was significantly larger than control group without aroma odor. From the t-test, however, there was no significant difference between two samples in terms of memory retention. Analysis of subjective evaluation revealed that the mood of participants is greatly affected by the preference of the odor of rosemary aroma. It was found that the participants tend to select negative words among many SD scales for odor they dislike in the impression evaluation of odor.