Proceedings of the Annual Meeting of the Cognitive Science Society

Diagram-based problem solving is an activity in which subjects solve problems that are specified in the form of diagrams. Since the diagram contains critical information necessary for problem solving, this is an activity that clearly requires reasoning with the diagram. Recent research on diagrammatic reasoning has uncovered many interesting aspects of this process. One such aspect that the authors have been exploring, by means of a set of verbal and gestural protocol analysis experiments, is the role of the diagram in guiding the reasoning process. The trajectory of reasoning is revealed both by the intermediate hypotheses gen?erated, and by the shifts of focus induced from problem solving protocols. In this paper w e focus on the protocols collected for a particularly interesting problem, one whose solution is ar?rived at through a pair of contradictory inferences. W e derived the reasoning trajectories of subjects by extracting the temporal order and spatial distribution of their intermediate hypotheses leading toward the final solution. These trajectories indicate that the spatio-temporal order of hypotheses depend on more than the device structure depicted in the diagram and inferred causation of events from the diagram. W e propose that subjects employ impUcit search strategies which together with their in?ternal goals to verify hypotheses and the need to replenish short term memory influence their reasoning trajectories