Note: this has only been tested on Firefox browsers -- Chrome works, but does not always reach 240 Hz.
Supplemental website for the HPG 2019 short paper: Temporally Dense Ray Tracing by Pontus Andersson, Jim Nilsson, Marco Salvi, Josef Spjut, and Tomas Akenine-Möller.

Hang on, measuring monitor refresh rate...

Explanation: Here we show the difference between rendering at 60 FPS (left) versus 240 FPS (right). Be sure to click the "240 FPS" radio button below. Focus, for example, on the fist of the robot, and follow it with your eyes. Most people can see that the fist is blurrier, and moves less smoothly, in 60 FPS compared to 240 FPS.

Desired frame rate: