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A mobile app devised by Korean scientists Kyungah Choi and Hyeon-Jeong Suk would allow teachers in LED-equipped classrooms to adjust the color temperature of ambient lighting on the fly, to fit the activities the students were undertaking at the moment. [Image: K. Choi and H. Suk, Opt. Express, doi: 10.1364/OE.24.00A907]

Scientists, educators, and policy makers routinely cast about for ways to improve the effectiveness of classroom environments. Now, an industrial-design team from the South Korean Advanced Institute of Science and Technology (KAIST) suggests a potentially simple way to boost classroom performance: tweak the lighting (Opt. Express, doi: 10.1364/OE.24.00A907).

KAIST scientists Kyungah Choi and Hyeon-Jeong Suk are not the first to look at the impact of light’s correlated color temperature (CCT) on human behavior, efficiency and performance. But most previous studies have focused on commercial or industrial environments. Choi and Suk wanted to find out if the impacts hinted at in previous efforts might map to the elementary-school classroom. In particular, they noted that the tunability of LED lighting—not something available with conventional fluorescent or incandescent illumination—might offer the prospect of “dynamic lighting” that could be adjusted to support different kinds of classroom activities.

Luminous ceiling

To dig into the problem, Choi and Suk designed a three-part study. In the first part, they hooked seventeen volunteer participants to an electrocardiogram (EKG) recorder to obtain baseline physiological readings at three CCTs: 3500 K, corresponding to conventional “warm” indoor incandescent lighting; 5000 K, analogous to the “cool” fluorescent lighting common in institutional settings; and 6500 K, a color temperature corresponding to daylight levels.

The measurements took place in a lab with an LED luminous ceiling, which allowed color temperature and illuminance to be precisely controlled. As expected from previous studies, the warmer, 3500 K lighting tended to be more “relaxing,” according to the EKG analysis, while the cooler 6500 K lighting was the most physiologically “arousing” of the levels measured.

Practical tasks

Next, the team attempted to quantify how these lighting colors, and their associated physiological implications, might affect the performance of actual classroom tasks. They undertook both a lab-based experiment in the luminous-ceiling room, with elementary-school-age subjects undergoing one experimental session lasting a total of 30 minutes, and a two-week field experiment in actual elementary-school classrooms fitted with tunable LED lighting.

In both cases, the experimental subjects were given two sets of tasks: an “academic” activity in which students were scored on their ability to solve a set of arithmetic problems within a timed interval; and a “recess” activity that involved face-to-face communication with peers for four minutes, followed by a self-report by the student of his or her perception of the elapsed time. (Previous studies have shown that physiological arousal can distort individual time perceptions; hence, the more accurate the student’s report of the time spent in the activity under a given illumination, the more relaxed the student was interpreted to be.)

Choi and Suk found that, in the limited and artificial lab experiment, there was no discernible difference in performance on the activities that corresponded to differing CCTs. In the longer-term study in actual classrooms, however, the difference was sharply drawn: the more daylight-like, 6500 K color led to significantly better performance on the academic activity, while the warmer, incandescent-like 3500 K color was clearly associated with a more relaxed performance in the less-structured recess activity.

There’s an app for that

Choi and Suk have proposed a simple dynamic-lighting setup for classrooms to put these preliminary findings into more practical application. The setup, which is tied into a mobile app, involves three lighting presets—“easy” (3500 K), “standard” (5000 K), and “intensive” (6500 K)—that could be adjusted on the fly by classroom teachers as students shifted to different kinds of activities.

The Korean team cautions that there is still work to be done to determine the impact of natural daylight fluctuations—which couldn’t be completely excluded in the field experiment—on what’s happening inside the classroom. They also stress there’s no one-to-one relationship between color temperature and academic performance. Nonetheless, the scientists believe that the study could offer “a good stepping stone” toward broader implementation of dynamic lighting in the classroom.