"In recent years, many researchers have provided scientific data in support of the belief that looking at "nature" has a positive influence on recovery from fatigue or stress. For example, Ulrich et al., (1991) reported that recovery from stress was faster and more complete when participants were exposed to natural rather than urban environments. Moreover, even a small amount of indoor plant may facilitate the recovery from mental fatigue (Shibata and Suzuki, 2001). However, it is not well investigated about which aspects (i.e. color, shape, or complexity) of natural elements cause these effects.MethodIn this study, we investigated how visual aspects of plant affect the participants' task performance and mood. To accomplish this, we used three room arrangements as independent variables: a room with (1) indoor foliage plants, or (2) imitations of foliage plants, or (3) a room with neither of these objects. In both two plants condition (1 and 2), three potted plants were placed in the room. The plants placed in natural plant condition were natural and alive. However, in artificial plant condition, those were imitations. In both plant conditions, participants were not informed whether the plants in the room were natural or artificial. If it is simply a shape of the plant that causes recovery effects, results in both two plants conditions should be the same.Undergraduate students (M=9, F=12) performed 2 sessions of Go/No Go task using Stroop style color words under one of the three room conditions. In this task, one of three color words (red, blue green) was displayed on the center of the 17-inch CRT display in one of these three colors. Participants were instructed to press the key when the displayed color word and its color were the same (). The interval between two color words was 1 sec. To assess participants' subjective fatigue, the General Arousal Check List (GACL; Matsuoka and Hatayama, 1989) was used. This questionnaire contains 20 adjectives to assess participants' mood state, and each of these 20 items is classified to one of 2 factors (Energetic Arousal(EA) and Tense Arousal(TA)).ProcedureEvery participant participated in all three conditions, one condition in a day. After participants arrived for their laboratory appointment, they were asked to take a seat, then they were given a general description of the experimental procedures and task instructions. After the electrodes for the physiological recordings were attached, and preliminary recordings were obtained, they were asked to complete the GACL questionnaire.When the participants completed the questionnaire, they engaged in the color word task for five minutes. Five minutes later, the participants were asked to complete GACL questionnaire again. Then, they were given a 3-minute break to rest and instructed not to stand up while they rested. When the time was over, participants were again asked to complete the GACL questionnaire. Following this, they engaged in the color word task for another five minutes. Again, participants were asked to complete the GACL questionnaire, and then asked to evaluate the room and the plants placed in the room. After the participants finished all three conditions, they were asked how they thought about the plants placed in the room, whether those were natural or artificial.Results and DiscussionTo determine the participants' subjective fatigue were affected by the plants, two 3x3x4 ANOVA was conducted using the scores of GACL (EA and TA) as the dependent measures, with using whether the plants in the room were real or artificial, or no plant (Objective Naturalness, ON), whether the participants thought those plants were natural or artificial, or no plant (subjective Naturalness, SN), and Time (pre- and post-task of each 2 session) as the independent variables. As for the EA score, a SN x Time interaction was significant (F(3,55)=2.80, p<.05). However, there were no significant effects for the TA score. In the follow-up analysis, the pre-task EA score of second session in the SN group was lower than others. These results suggest that whether the participants thought the plants were natural or artificial have more effects on participants?f mood rather than whether plants were a real thing or not. That is, a positive influence by nature on recovery may be caused not simply by looking at nature but people's belief that looking at nature has an restorative effect."