This study investigated the effect of collaboration from the view points of the characteristics of tasks and the interdependence structure among problem solvers. Previous studies have suggested that representational change was facilitated when two persons worked at different levels: a task level and a meta-task level. In the present study, this hypothesis was experimentally examined. 20 participants were assigned to a single condition and 40 were assigned to a pair condition. They were asked to solve a map-construction problem, which required representational change. In the pair condition, one participant was instructed to work as “a problem solver” involving task level activity, while the other worked as “a supporter” involving meta-task level activity. The results showed that representational change occurred more often in the pair condition than in the single condition. The percentage of representational change in the real pairs was significantly higher than that of the hypothetical pairs, which was calculated by the data of the single condition. Protocol analysis revealed that problem solvers engaged in making image from text information more often than supporters, while supporters mainly evaluated the image proposed by problem solvers and suggested a way of solving the problem.