If you’ve ever looked at a clock and been tricked into thinking that time is standing still, you may have experienced "Saccadic Masking," a type of temporal illusion. It typically occurs following rapid-eye-movement (REM), where the brain produces a still image rather than a blurred one. It might only seem like a second before the hand starts ticking again. However, these seconds lost can add up to a whopping 40 minutes a day. While this illusion does technically happen every time we move our eyes rapidly, a lot of the time it’s undetectable. We’re aware of this illusion more when we’re looking at a clock because we expect the tick-tock motion that accompanies it. However, the illusion can be found elsewhere. For example, when in a moving vehicle if the eye movement can be timed to match the vehicle’s speed, objects that initially were blurry will appear distinctly. Similarly, you can focus on and track a single blade of a ceiling fan as it spins around if it isn’t moving too fast. Of course, since this phenomenon requires REM, the clear view will only last a moment.
