Sentence:  Is an infant who delights in such repetitive actions as swatting a brightly colored mobile or making a toy duck quack engaging in <WSD>"planful</WSD>" or "intentional" behavior? Piaget said no: the secondary circular reaction is not a fully intentional response, because the interesting result it produces was discovered by chance and was not a purposeful goal the first time the action was performed. 
Meaning of the word marked with <WSD> tags:  Intentional.