Combinatorial skills: converging developments over the second year.

Toddlers' combinatorial abilities were examined over several behavioral domains as a function of age (20 and 27 months) and task demands (familiarity of components, length of combinations, complexity of combinations, centered/decentered focus of action, behavioral domain). 6 specific domains were represented. Children's combinations were observed during elicited imitation in 4 of the domains (object play, pretense, social play, motor play) and spontaneous production in 2 others (language and peer-directed social overtures). Relative to younger children, older children produced more combinations of at least 2 or 3 discrete behaviors in every domain, including peer interaction, and fewer noncombinatorial behaviors. Consistent relations were also found across domains for production of combinations, that is, children who produced more combinations in one domain also did so in others. Finally, 4 of the 5 manipulated task demands proved to affect performance. Results are discussed in terms of possible age-related constraints on combinatorial skills that operate at a general, cross-domain level during toddlerhood.