The role of darkness in students' conceptions about light propagation and vision

Light propagation is one of the most fundamental physics concepts utilized in astronomy education. One variable that has not been directly incorporated into prior research on students' conceptions about light propagation is exposure to complete darkness, both prior to and during instruction. The common perception that 'light is not a prerequisite for sight' may be considered a faulty ontological assumption due to a lack of prior experience with total darkness. During the Fall 2005 semester, a research pilot study was conducted on the relationship between total darkness and vision using 154 students from University of Delaware's Black Holes and Cosmic Evolution course. The data is complex and led to many significant findings. Analysis of these findings is enriched by exploring student written responses and interview data. The results of the study indicate that student's who had prior exposure to total darkness provided more accurate representations of light propagation from luminous and non-luminous sources than students who did not have such exposure. The research conducted on the effect of classroom lighting (e.g. providing experience of total darkness) suggests that both naive and learned students have a fragile understanding of the relationship between light, darkness and vision and that students may benefit from careful scaffolding of the experience of total darkness into instruction on light and optics. Results show that student pictorial representations progressed toward more normative models after exposure to total darkness, but overall explanations shifted away from understanding about reflected light toward explanations involving illumination. In addition, the results reveal that students' experiences with low-light conditions may have created physiological artifacts in students' conceptualization about light and vision. While attempting to assimilate the experience of total darkness into their conceptual framework, many students conditionalized their answers to explain their observations.; This paper will report on the findings of this study, analyze the results in the context of related literature and provide recommendations for further research. This paper will reveal students' understanding of the connection between light and vision and the challenges faced in comparing naive ideas to organized frameworks (textbook) of understanding light and vision. Excerpts from student questionnaires and interview data will be used to demonstrate how phenomenological experiences shape naive student's ideas about light and vision and how these ideas can be mapped to normative ideas to show the nature of students' thinking about light and vision.