What to Look For in a Mobile Touch Screen
A good layout for a touch screen on a mobile phone lets you thumb through buttons quickly and accurately. A lousy layout causes you to dial wrong numbers.
A study of people using touch screens finds that differences in button size and location can promote fluid manoeuvring or clumsy fumbling. From the results, researchers have come up advice on key layouts that make touch screens easy to use.
Here's what to look for in a useable touch screen:
- Key Size – Keys at least 7 millimetres wide (one-quarter inch) are best for speed. If you really hate making mistakes, then 10-millimetre keys (0.4 inches) are even better.
- Frequently Used Keys – The keys you use most, such as shortcuts for text messaging or phoning, should be at the screen's center. People find that's a quick and convenient place for thumbs to reach.
- Keys Needing Accuracy – Keys you really don't want to make a mistake hitting, a camera shutter button for instance, are best located on the left side of a screen. That's where people make the fewest errors pressing keys.
- Areas Without Keys – Keys located along the screen edges, especially in corners cause frustration. You'll likely be slow and make mistakes when aiming for keys there. Instead, touch screen edges make good places for indicators, progress bars and notifications.
Yong S. Park and Sung H. Han. 2010. Touch key design for one-handed thumb interaction with a mobile phone: Effects of touch key size and touch key. International Journal of Industrial Ergonomics. 40(1): 68-76.