When you roll your “R”s while looking at a digital clock why do the digits vibrate?

824 views

If you look at a digital clock or any other display like that and roll your Rs or vibrates your lips, the digits seem to vibrate violently as well while nothing else in your vision moves. Why does that happen?

In: Biology

2 Answers

Anonymous 0 Comments

Your brain does a bunch of correcting of your eye’s sensory input, and 2 in particular that come into play and kind of conflict here.

First is that when your head or eyes are vibrating your brain compensates to steady the picture a little bit.

Second is that an LCD clock doesn’t display all of the lit segments at the same time, but rather it cycles between powering the ones that should be lit really quickly (this has to do with maintaining brightness out of a limited number of circuits); normally, like the refresh rate on a TV or monitor, this happens too quickly for you to detect, so you typically just see a uniformly lit LCD display.

When you combine the two effects, you see them light up when the clock is in a slightly different part of your brain and it can’t quite keep up, and it corrects wrong (because LCD clocks aren’t common in nature).

Anonymous 0 Comments

As you roll your Rs, your head vibrates. This makes everything you see appear to vibrate. You only notice it in whatever your vision is focussed on, which in this case are the digits of an alarm clock. Also, because your brain knows the entire room isn’t vibrating, but knows something is vibrating, it tricks itself into thinking what you’re focussed on is vibrating.

This is all speculation btw.