The Journal of Experimental Education, 2000, 69(1), 36-56 Effects of High and Low Prior Knowledge on Construction of a Joint Problem Space CINDY E. HMELO ANANDI NAGARAJAN Rutgers, The State University of New Jersey ROGER S. DAY University of Pittsburgh ABSTRACT. The participants were 4th-year medical students designing a clinical trial to test a new hypothetical anticancer drug. They worked with the computer sim- ulation the Oncology Thinking Cap in facilitated groups that differed in terms of their prior knowledge. Both groups engaged in constructive activity and reached similar endpoints. The groups differed qualitatively in how they went about con- structing and navigating the joint problem space. The high-prior-knowledge group used their knowledge to help them construct plans, evaluate their actions, and stay focused on the goals of the experimental design task. The low-prior-knowledge group searched through the data exhaustively and used them to generate their plans. They were unsystematic in their planning and interpretation. They used the computer rep- resentations in their reasoning and worked at mapping the connections between the representations. The computer scaffolding played an important role for both groups, but the facilitator played a greater role in the low-prior-knowledge group. Key words: Constructivism; prior knowledge; sociocultural theory FOR A GROUP OF LEARNERS to solve an unfamiliar problem, they must construct a shared understanding that should be affected by their prior knowledge and tools available for problem solving. We extended the work on prior knowl- edge in individuals to understanding how learning occurs in collaborative groups as we examined how medical students learn experimental design using a com- puter simulation environment. Our perspective on peer collaboration is strongly influenced by sociocultural theory. We also borrowed from the cognitive tradition as we examined the collaborative strategies used in an experimental design task by high- and low-prior-knowledge groups. 36