A skill involves perceptual-motor components, often referred to as lower-order skills, and cognitive components, referred to as higher-order skills. To play the piano, for example, we first have to learn the perceptual-motor skill of hitting the keys with our fingers. Gradually we build up this skill, using the fingers to hit different keys fluently in different sequences. But at the same time, we need to activate the cognitive skill of reading musical notation, or of bringing to memory a particular melody in order to direct the movements of our fingers. We also need to pay attention to feedback, for example, wrong notes, and adjust our finger movements accordingly.

We have to learn to integrate lower-order skills with higher-order skills. As we perform the perceptual-motor skills more automatically, with less conscious attention, we can start to assess our performance more carefully against some goal we want to achieve. For example, our goal may simply be managing to play the left hand and right hand parts together, or it may be to make our playing more expressive by introducing differences of pace and loudness.

In performing a skill, we constantly set and adjust goals, juggling competing demands for our attention. Experts at a skill do this effortlessly; it's rather more problematic when skills are less proficient. If you are a regular (proficient) driver, you can probably drive while communicating effectively with a passenger. However, if your driving skills are not proficient, or you are trying to communicate in a second language you do not master, then doing the two things at the same time is likely to cause performance problems!

In developing a skill, then, we have to:

• integrate a variety of subskills, both perceptual motor and cognitive ('a complex, well-organised pattern of behaviour');
• develop fluent performance ('carrying out behaviour smoothly');
• develop the ability to change our performance ('carrying out behaviour adaptively') depending on our goals.