The prehistory of discovery: precursors of representational change in solving gear system problems.

Microgenetic research has identified 2 different types of processes that produce representational change: theory revision and redescription. Both processes have been implicated as important sources of developmental change, but their relative status across development has not been addressed. The current study investigated whether (a) the process of representational change undergoes developmental change itself or (b) different processes occupy different niches in the course of knowledge acquisition. College, 3rd-, and 6th-grade students solved gear system problems over 2 sessions. For all grades, discovery of the physical principles of the gear system was consistent with theory revision, but discovery of a more sophisticated strategy, based on the alternating sequence of gears, was consistent with redescription. The results suggest that these processes may occupy different niches in the course of acquiring knowledge and that the processes are developmentally invariant across a broad age range.