Introduction We are constantly bombarded by stimulation. Even a simple scene presents our senses with a host of shapes, colours and sizes of objects and people. Consider a lecturer working in her office. She hears the roar of traffic outside, people talking in the corridor, doors slamming and the constant hum of a computer. She might be feeling thirsty and a little hungry. Memories – some personal, some work related – probably fill her mind. A number of problems probably need speedy solutions. Some may be obvious, others not. Students are lining up outside the door, colleagues are telephoning and emails are queuing up for response. How is it she doesn’t get overwhelmed by these sights, sounds, memories and thoughts?