No-one looks at the screen

Even the best displays quickly make your eyes tired, because...

a. They're grainy

A good resolution is about 100 dots per inch - that's a third of the sharpness of newsprint.

b. They flicker

Most people have to run a CRT display at high refresh - 75Hz or more - to get decent results. LCD screens are better, but reading off screen is always slower and more tiring than reading off paper. Also, some people are particularly sensitive to screen flicker.

c. Staring at screens is bad for your eyes

Looking at a screen from the same distance for long periods leaves our eyes weak, dry and sore.

(To protect your vision, experts recommend taking a short break from the computer every 20 minutes, walk around. Focussing at different distances strengthens the eye muscles.)

How users cope

Computer users quickly start learning time-saving shortcuts to try to make life easier on the eyes. In order to reduce the time we spend looking at the screen, we:

• are very impatient
• make quick decisions
• scan pages, instead of reading

Good design appreciates these considerations, and deliberately helps users have a quicker, less tiring experience.