Advantages and artifacts of high-speed OLED monitors for vision, eye-tracking, and EEG research

The recent introduction of organic light-emitting diode (OLED) monitors with refresh rates of 240 Hz or more opens new possibilities for their use as precise stimulation devices in vision research, experimental psychology, and electrophysiology. These affordable high-speed monitors, targeted at video gamers, promise several advantages over cathode ray tube (CRT) and liquid crystal display (LCD) monitors. Unlike LCDs, OLEDs have self-emitting pixels that can show true black, resulting in superior contrast, a broad color spectrum, and wide viewing angles. More importantly, the latest OLEDs offer excellent timing properties with minimal input lag and rapid transition times. However, OLED technology also has potential drawbacks, such as auto-brightness limiting (ABL), where luminance changes with the number of illuminated pixels. This study characterized a 240 Hz OLED monitor (ASUS PG27AQDM) in terms of its timing, temporal independence, spatial uniformity, viewing angles, warm-up time, and ABL behavior, and compared it with CRTs and LCDs. Results confirm excellent temporal performance, with CRT-like transition times, wide viewing angles, and good spatial uniformity. We show that ABL can be prevented with appropriate settings. However, we also report a novel type of luminance artifact on OLEDs, where high-contrast stimuli, shown for long durations, can create image persistence via localized warming or cooling of the panel. Finally, we demonstrate the monitor's benefits in two time-critical paradigms: rapid invisible flicker tagging (RIFT) and saccade-contingent display changes. The latest consumer OLEDs provide precise and cost-effective stimulation devices for time-critical experiments, although some caution is warranted in experiments involving long exposures to high-contrast stimuli.