7
votes
Input lag AB test
Have you ever wondered how little of a difference of input lag you can perceive? With this tool, you can find out.
The screen is split into two halves, and one of them has an artificial amount of input lag (default 50 ms, you can change it) added to the mouse cursor. Figure out which side feels laggier and click on it. After 25 trials, it will show your results. If you can consistently score at least 18/25 correct at a certain amount of lag, then you can probably perceive it. I can go as low as 20-25 ms on my 144 hz monitor.
Be sure to edit one of the files as shown here to disable v-sync, or if you trust me you can download my copy.
I got 21/25 at 50ms, 17/25 at 25ms with a standard 60hz monitor. Interesting test, thanks for posting it.
First try at each: 25/25 at 50ms, 25/25 at 33ms, 24/25 at 25ms, 25/25 at 16ms(!), 13/25 at 8ms. I'm using a bog-standard (but several years old) 60Hz laptop display. Interestingly I had to look away for a couple of seconds after every few trials at 33ms and below, else the difference became really hard to spot.
Probably worth noting that the overall latency inside the application was noticeably higher than the rest of my system – I was running it windowed in Wine (since I'm not on Windows and I can't be bothered to install LÖVE), which will have added some latency.
Damn that's really impressive, especially with extra latency overall.