6. Attention span

The human brain tends to focus on events whilst ignoring others.

There is a famous test where a group of people are asked to view a video clip of a basket ball game and are told to count how many passes are made.

© Daniel J Simons

So everyone concentrates and counts away. But then the psychologist asks them 'Who saw the dancing gorilla?' Amazingly out of a group of 20 people only 1 actually saw a man in a gorilla suit dancing through the basket ball game!

It is called 'inattentional blindness'. The brain simply cannot see everything when distracted. People have a limited attention span.

The same principle applies to designing an interface -

• Only present information that is relevant at that instant
• Do not cause distractions