Problem decomposability as a factor in complexity of the dimensional change card sort task

According to cognitive complexity and control (CCC) theory complexity depends on number of levels of a hierarchy of rules. According to relational complexity (RC) theory complexity is a function of the number of related variables in the task, and the most difficult tasks are those in which there is a constraint on decomposition into simpler subtasks. One hundred and twenty, 3–6-year old children were tested on the standard dimensional change card sort (DCCS) task, or a modified version, the DecompDCCS, in which the dimensions could be decomposed into subtasks. The standard version requires two levels of a hierarchy to be processed, and is ternary relational according to RC theory, whereas the subtasks of the DecompDCCS are binary relational. The DecompDCCS was easier than the DCCS for 3–4 year-olds, but all 5–6 year-olds succeeded on both. The results indicate that decomposability into simpler subtasks, as suggested by RC theory, is a factor in difficulty of DCCS. The role of decomposability in other tasks that are persistently difficult for young children is discussed.