A sample of 315 children aged between 6 and 9 years participated in a 5-month longitudinal study aimed at investigating constraints on representational flexibility as observed in drawing behaviour. The study specifically looked at how external interventions affected children's representations over time. The intervention involved showing children various examples of pretend people in relation to Karmiloff-Smith's (1990) task of requesting children to operate on their normal person drawing procedures. The study confirmed that knowledge introduced exogenously was only beneficial immediately after the intervention. Over time, in contrast to the older children, the younger children reverted to their internal representations that were specified as sequentially fixed lists. The intervention did not promote transfer of learning to the analogous task of drawing pretend houses. The study suggests that exogenous provocations of behaviour are driven by adjunctions, and that reiterated cycles of representational redescription must occur before the externally mediated knowledge becomes flexibly manipulable.