A high-speed OLED monitor for precise stimulation in 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 the cathode ray tube (CRT) and liquid crystal display (LCD) monitors commonly used in these fields. Unlike LCDs, OLED displays have self-emitting pixels that can show true black, resulting in superior contrast ratios, a broad color gamut, and good viewing angles. More importantly, the latest gaming OLEDs promise excellent timing properties with minimal input lags and rapid transition times. However, OLED technology also has potential drawbacks, notably Auto-Brightness Limiting (ABL) behavior, where the local luminance of a stimulus can change with the number of currently illuminated pixels. This study characterized a 240 Hz OLED monitor, the ASUS PG27AQDM, in terms of its timing properties, spatial uniformity, viewing angles, warm-up times, and ABL behavior. We also compared its responses to those of CRTs and LCDs. Results confirm the monitor's excellent temporal properties with CRT-like transition times (around 0.3 ms), wide viewing angles, and decent spatial uniformity. Additionally, we found that ABL could be prevented with appropriate settings. We illustrate the monitor's benefits in two time-critical paradigms: Rapid "invisible" flicker stimulation (RIFT) and the gaze-contingent presentation of stimuli during eye movements. Our findings suggest that the newest gaming OLEDs are precise and cost-effective stimulation devices for visual experiments that have several key advantages over CRTs and LCDs.