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At low refresh rates ( below 50 Hz ), the periodic scanning of the display may produce an irritating flicker that some people perceive more easily than others, especially when viewed with peripheral vision.

Computer displays and televisions with CRTs driven by digital electronics often use refresh rates of 100 Hz or more to largely eliminate any perception of flicker – see flicker-free.

Non-computer CRTs or CRT for sonar or radar may have long persistence phosphor and are thus flicker free.

If the persistence is too long on a video display, moving images will be blurred.