Proceedings of the Annual Meeting of the Cognitive Science Society

In order to understand conceptual change, it is crucial to understand how people respond to anomalous information. The purpose of this paper is to present a framework for understanding how people respond to anomalous data and why they respond as they do. First, w e present a taxonomy of seven responses to anomalous data. Second, we present an analysis of eight factors that are hypothesized to influence which of these seven responses an individual will choose. Finally, w e present the results of an experiment that investigates severjj of these eight factors. A key to understanding conceptual change is understanding how people respond to anomalous information. Information that contradicts an individual's current beliefs is important because without it, an individual has no need to alter current conceptions. Without the goad of anomalous information, current conceptions are perfectly adequate for understanding the world. A particularly important form of anomalous information is anomalous data. Anomalous data have played a central role in conceptual change in the history of science (Kuhn, 1962) and in science education (Chinn & Brewer, in press). Moreover, most artificial intelligence systems that model scientific discovery and theory change use jmomalous data to trigger the theory change process (e.g., Kulkarni & Simon, 1988). Chinn and Brewer (1992, in press) have proposed a detailed taxonomy of possible responses to emomalous data. W h e n an individual w h o holds theory A encounters anomalous data, which may be accompjmied by an alternative theory B, the individual can choose one of seven responses to the anomalous data: 1. Igitore the data. 2. Reject the data because of methodological flaws, random error, or alleged fraud. 3. Exclude the data from the domain of theory A b asserting that theory A is not intended to explain th data. 4. Hold the data in abeyance, i.e., concede that theory A cannot explain the data at present but asset that theory A will be elaborated in the future so tha it can explain the data. 5. Accept but reinterpret the data so as to make thi data consistent with theory A. 6. Accept the data and make minor, peripheral changes to theory A. 7. Accept the data and change theories, possibly ti theory B. Of these seven responses, only the last two involv any change m theory A , and only the last produces change that can be called conceptual change. Th first six responses are theory-preserving response because the individual discounts the anomalous data in order to protect theory A. In this paper, we address a crucial issue in conceptual change: What causes people to respond t( anomalous data as they do? For example, why doe an individual reject data in one instance, reinterpret data in another instance, and change theories in ye another instance? W e propose a set of eight factor that influence h ow people respond to anomalous data then we report the results of an experiment designei to investigate several of these factors.