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Temporal light modulation (TLM), commonly referred to as "flicker" can create visual discomfort, worsened reading time and accuracy, erratic eye movements, and headaches, among others. In most new construction projects, LED luminaires are being specified in conjunction with a pulse-width modulation (PWM) dimming system. While PWM systems have controllability and energy efficiency advantages over constant current dimming systems, they intentionally introduce TLM into the space due to the varying duty cycle of the LED waveform. To evaluate the impact of TLM likely present in workspaces with LED dimming, we measured reading time and the number of reading mistakes made during a reading task when participants were exposed to LED luminaires with different levels of duty cycle that mimic those in a traditional office setting. Interestingly, there was not sufficient statistical evidence to infer a relationship exists between the duty cycle of an LED light source and the reading time and accuracy of the participants. These findings contribute to the inconsistent results on the effects of TLM in the architectural lighting literature, likely due to the many combinations of environmental variables possible for evaluating human performance under TLM. This suggests that the development of metrics, predictive equations, and TLM standards is necessary for refining experimental research in the area and ultimately understanding the effects of pulse-width modulation on human visual performance.
