There is a light experiment where a coloured disk with equal red, blue and green sectors is rotated. As the rotational speed increases the coloured sectors coalesce into a white disk, thus demonstrating that white light may be considered to be the sum of three primary colours.

I tried doing this using modern technology - a coloured disk rotating on a computer screen. It didn't work, no matter how fast the disc notionally rotated. I seemed to be getting a slow  stroboscopic effect rather than coalescence. 

Is this caused by a feature of computer screens?