关键词: 室内照度, 视空工作记忆, 视空能力, 警觉性, 主观情绪

Abstract: Research has shown that ambient lighting has a great impact on hunan non-visual effects, such as hormone secretion, physiological status and cognitive performance. Many studies found that high illuminance could enhance task performance, subjective alertness and mood. As regards the cognitive performance, however, most previous studies focused primarily on the influence of indoor lighting on simple vigilance tasks and working memory task, especislly the verbal working memory. Little is known about the impact of indoor lighting on the visuospatial working memory(VWM) though it plays a crucial role in storaging and processing spatial informance in our daily life. Further, spatial ability as another important ability in processing spatial information, mainly refers to the skill in representing, transforming, generating, and recalling nonlinguistic information, including spatial perception, mental rotation and spatial visualization. Though several studies have explored the effect of correlated color temperature on spatial ability, few has examined the effect of indoor illuminance on individual’s spatial ability during the daytime. Moreover, some studies also found that time of day may as a moderator in the lighting effects. Thus, the present study explored the impact of illuminance on visuospatial performance using VWM and spatial ability tasks and whether these lighting effects were moderated by time of day. A 2(Illuminance: 200 lx vs 1000 lx)×2(Time of day: Morning vs Afternoon) mixed group design was employed in the current study to investigate the effect of illuminance and time of day on healthy adults’ visuospatial performance, mood and alertness. Illuminance was the within-subject factor. A total of 34 subjects participated in the experiment according to the selection criterion. All participants should complete two light sesssions on separate days during the same timeslot in the morning or in the afternoon. VWM tasks consisted of the Coris block task and the dot memory task. Spatial ability test battery included the Hidden Pattern test, Card Rotation test and Embedded Figure test. Several scales like PANAS and KSS as well as the PVT and CFF were accessed participants’mood, alertness and visual fatigue respectively. Results revealed that the interaction between illuminance and time of day on objective alertness was significant, indicating that the reaction time of PVT was shorter under the bright lighting condition in the afternoon. However, no significant effect of illuminance and time of day on subjective alertness was observed. The main effect of illuminance on CFF value was significant that bright light exposure induced less visual fatigue compared to the dim light. Concerning visuospatial performance, the main effect of illuminance on Coris block task showed that the number of correct recalled position was significantly larger under bright light than under dim light condition, while no significant effect on other visuospatial tasks were observed. In summary, the results revealed that daytime bright light could improve participants’ alertness only in the afernoon. The beneficial effect of bright light on visuospatial performanc was only observed on the VWM, but not on the spatial ability. These results suggest that effects of indoor illuminance on cognitive performance may dependent on type of task.

Key words: indoor illuminance, visuospatial working memory, spatial ability, alertness, subjective mood