Introduction When we first start learning a complex task, such as driving a car, there seem to be too many component tasks involved. We are overwhelmed by the combination of steering, operating the clutch, monitoring the road and changing gear. With practice, less and less conscious effort is necessary. Steering round a corner while operating the clutch and changing gear is accomplished in one operation, often while we converse with the passenger. Clearly, something changes with practice, driving the car seems to be controlled in a very different way by the experienced driver than the learner. The expert can drive while talking, the novice cannot; the expert can control two tasks yet the novice has difficulty with even one. What has been learned by the expert? When driving a new car, the expert may initially switch on the windscreen wipers every time they intend to indicate. It can take many hours of driving the new car before the new configuration of controls is learned. The expert has become able to make many actions such as moving the indicator lever automatically, but when one of these action needs modifying, time and practice is needed all over again. The automatic response has to be deliberately modified, i.e., control has to wrested from the automatic mode by conscious control. So, what is learnt with practice and what can this tell us about the nature of the systems that control information processing?