Philosophers and scientists have across the ages been amazed about the fact that development and learning often lead to not just a merely incremental and gradual change in the learner but sometimes to a result that is strikingly different from the learner's original situation: amazed, but at times also worried. Aristotle, for example, notes that excellent and virtuous behaviour is considered by thinkers like Plato to require conscious and rational control in all persons and occasions, whereas Aristotle himself observed that sustained practice often leads to a form of habituation which renders such control of an agent unnecessary, yielding in fact a very different situation (cf. Aristotle, 1984: Ethica Eudemia 1216 b 6-10). More recently and from a completely different perspective, a seminal brain imaging study comparing brain activation patterns in novices and experts performing identical tasks showed that increased expertise correlated with drastic changes in functional brain anatomy. Indeed, the differences were so large that the authors concluded that novices seem to perform outright 'different tasks' from those that experts do: the functional anatomy of experts was both more efficient and task-relevant networks were more associated with other, potentially relevant, functional networks (Petersen et al., 1998).Such philosophical and empirical perspectives give some insight into what happens when a novice is transitioning to a stage of expertise. Generally, this implies that increased skill and expertise support better results and a more flexible performance, in part because these allow an agent to withdraw part of her attention and other cognitive resources from the tasks involved, enabling her to devote those resources to supporting, or completely different, tasks. This implication of expertise (which here includes also skill learning, even though the two are not identical in all respects) comes naturally in many cases after many hours of exposure and practising particular behavioural or cognitive tasks. In the case of humans, targeted training and education contribute in specific ways to the development of expertise as well. 1 We are apparently capable of accomplishing drastic changes