SUMMARYA complex problem, consisting of 12 graded elements, was presented to normal children of 1 1/2–5 yr and to severely subnormal children, in order to attempt to elucidate some aspects of early cognitive development. Strategies adopted have been analysed in terms of the plan and TOTE unit concepts proposed by Milleret al.It is suggested that an early phase when a repetitive behavioural sequence is directed towards an externally given end‐point, is followed by one in which the sequence is terminated at the appropriate point by the interpolation of a manipulative, or observing action after each repetit