‘Executive functions’ are not straightforward to define. In early theoretical accounts, such as that of Baddeley and Hitch (1974), the central executive was conceptualised as a unitary system. However, the unitary concept of the central executive has undergone ‘fractionation’ (Baddeley & Della Sala, 1996, p. 1402) into a much wider range of processes which are subsumed under the term ‘executive function’. For example, Miyake, Friedman, Emerson, Witzki, & Howerter (2000) carried out a confirmatory factor analysis of performance data from adults and found evidence for inter-related but dissociable contributions from the executive functions of shifting of attention, updating of working memory representations, and inhibition. Andersson (2008) offers an even more fine-grained analysis: ‘The key elements of executive function include (a) anticipation and deployment of attention; (b) impulse control and self-regulation; (c) initiation of activity; (d) working memory; (e) mental flexibility and utilisation of feedback; (f) planning ability and organisation; and (g) selection of efficient problem solving strategies’ (Andersson, 2008, p. 4).