Screen vision

[davver]

Why, when munching on, say, a particularly crunchy biscuit, or when cleaning one's teeth with an electric toothbrush, do computer screens appear to flicker? I guess it is something to do with the jarring of the jaw, and then the skull, and then the eyes or the optic nerve, but in that case why does the brain manage to stabilise the sight of everything else, but not what is on the screen? I don't know if it works with television screens as well.

[Cockney_si]

I used to get this when I was a kid and my folks could never understand why I thought that when I hummed load enough the tv screen would shake.

It's just vibration of your eyeballs!

[davver]

Yes but why doesn't everything else shake too?

Is it because the screen is actually a series of flashes, whereas other images actually exist contiually?

[Cockney_si]

Yeah I guess it must be, the screen flickers at a certain rate (measured in Hertz) and that's why only the screen wobbles and people think we're bonkers!