A display refreshes at fixed intervals. The theoretical time between refreshes is:
That matters because a visual change can only become visible when the display actually updates. Higher refresh rates provide more opportunities per second for that change to appear.
Two monitors running at the same refresh rate can still have different internal processing delays. Research measuring gaze-contingent displays found meaningful end-to-end latency differences among monitors, even when some shared the same refresh rate.
Computer reaction testing also includes input latency. A mouse click must be detected by the device, driver, operating system and browser before the page can timestamp it.
It can reduce one source of waiting time and can make motion and visual updates feel more immediate, but the exact improvement in a browser reaction test is not fixed. The stimulus may appear at different points in a refresh cycle, and other hardware/software delays may dominate.
A 2024 experimental preprint comparing 30, 60, 120, 144 and 240 Hz in an FPS task found a clear performance penalty at 30 Hz, while differences among the higher rates were less decisive. That is a reminder that the relationship between refresh rate and actual human performance is more complicated than “double the Hz = double the performance.”
Continue with: 60 Hz vs 144 Hz vs 240 Hz · Does FPS affect reaction time? · Input lag vs reaction time · Mouse polling rate.