Students' responses to experimental evidence based on perceptions of causality and availability of evidence

Abstract

This study investigates students' causal beliefs about the relation between certain variables in an electric experiment and seeks to determine the degree to which their tendency to make either idea-based or evidence-based statements about the experiment depends on their having had a prior belief about the causal efficacy of that variable. Fourteen eighth-grade students of both sexes from an initial sample of 49 were presented with experiments and interviewed to determine whether their responses were idea-based or evidence-based, and whether these responses were correlated with the type of prior idea they had held about that variable (causal or noncausal). We found that 34% of all responses were idea-based despite the presentation of physical evidence. We also found that students who had previously thought that a particular variable would not affect the outcome of the experiment (i.e., who had a noncausal idea for that variable) were more likely to make idea-based responses than students who had causal ideas. Furthermore, students tended to make fewer evidence-based responses when evidence was unavailable rather than available. © 1997 John Wiley & Sons, Inc. J Res Sci Teach 34: 57–67, 1997.