The symposium on "Visual Reasoning in Discovery, Instruction and Problem Solving" will consist of three talks focusing on the role of visual reasoning in higher level cognitive processes. As this is a newly emerging research area spanning cognitive science and artificiaJ intelligence, the symposium is designed both to inform and to stimulate interest, discussion, and further enquiry. The speakers will consider visual reasoning in three areas: scientific reasoning and discovery, learning and instruction, and problem solving. The talks will show how several different types of data can contribute to a clearer understanding of processes, mechanisms, and strategies underlying visual reasoning. First, N2uicy Nersessian will cover the discovery aspect by providing a historical view on visual representation in creative scientific reasoiung. Next, Rogers Hall will cover the educational aspect by laying out a set of genered educational questions concerning the role of representational forms, and discussing studies of how people coordinate representational resources while working on problems in different instructional and work settings. Finally, Mary Hegarty and Hari Narayanan will together cover the problem solving cispect from both experimental and computational perspectives.

This paper reports on an exploratory study of diagrammatic reasoning. Concurrent think-aloud protocols and gestures of subjects solving a set of device behavior hypothesis problems presented as labeled diagrams were collected. In addition to analyzing verbal protocols, the gestures and marks made by the subjects were examined and used to annotate encoded verbal data. A model of diagrammatic reasoiung in this task is proposed and compared with results of analyzing the protocols. Besides lending support to results of previous experimental studies, this study also revealed some interesting aspects of diagrammatic reasoning that merit further investigation.

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

The constructivist paradigm, which views learning as an active process in which students participate by engaging in activities that facilitate the construction of internal representations, is fast gaining currency as an innovative and effective way to overhaul classroom instruction. One way to promote constructivist learning is to firmly embed the acquisition of knowledge in realistic and stimulating contexts that challenge students to explore a variety of issues and employ a variety of their skills. This symposium will focus on four approaches (anchored instruction, casebased reasoning, goal-based scenarios, and problembased learning) designed to contextualize learning in this fashion. They do so in different, yet related ways. Examples of these approaches, ways in which they are similar and different, and important concerns regarding their effects on student learning and performance will be some of the issues that panelists will address. The panelists in this symposium are: Ray Bareiss, Institute for the Learning Sciences, Northwestern University; Cindy Hmelo, Janet Kolodner, and Hari Narayanan, EduTech Institute, Georgia Institute of Technology; Vimla Patel, Center for Cognitive Science, McGill University; and Susan Williams. School of Education and Social Policy, Northwestern University.