Figure 1.

Diagrammatic representation of rules for each condition on branching task redrawn from Koechlin et al. [18]. In this version of the task participants completed six runs of the control condition then progressed onto the delay, dual-task and finally the branching conditions. Control condition: subjects had to decide whether two successively presented letters were also in immediate succession in the word 'tablet' (only upper-case letters were presented). Delay condition: subjects had to ignore lower-case letters which were used to occasionally delay the response required by the upper case letters. Dual task condition: subjects had to respond as in the control condition for both upper- and lower-case letter series with one exception. Subjects had to decide whether every first letter indicating a case change was the letter T (or t). Branching condition: subjects had to respond to upper-case letters exactly as in the delay condition and to lower-case letters exactly as in the dual-task condition.