Publication Date


Document Type


First Advisor

Brown, Megan R.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geographic and Atmospheric Sciences


Diagrams are important tools for conveying information in geoscience education. Choosing what imagery to use and assessing its effectiveness is not straightforward. A diagram needs sufficient affordances (i.e., details, dimension) for the viewers to comprehend the intended message without adding too many details that will confuse and distract the viewer. Prior research suggests that the viewer’s knowledge and experience impact how diagram affordances are interpreted. Understanding this interaction between knowledge, context, and diagram affordance is critical for education and assessment.To investigate how changes in affordances affect student interpretation of images, we surveyed undergraduate students (N = 201) in introductory Earth Science courses. The survey included multiple-choice and click-on-diagram questions about surface water and groundwater features portrayed in diagrams accompanying the questions. The affordances that were varied include dimensionality details (e.g., two- or three-dimensions) and shading patterns (e.g. water represented by blue, unconfined aquifer represented by gravel). All participants received all versions of the diagrams but presentation order was counterbalanced such that participants were randomly assigned to one of three groups to detect ordering effects. The number of correct responses was compared across the related diagrams and was used to gauge their efficacy. Significance of the difference in the number of correct responses for related diagrams was measured using a Pearson’s chi-square test of independence. The ordering effects were assessed using a Kruskal-Wallis one way analysis of variance test. Results showed that affordances added to the Intermediate and Complex river diagrams increased correct responses to questions about erosion, but did not affect questions about deposition. None of the affordances added to the groundwater diagrams led to significant differences in the number of correct answers to the accompanying questions. Differences in responses between groups was found only for the deposition questions, indicating ordering effects may have influenced responses. Results of this study provide researchers, instructors, and instructional designers with evidence on how affordance and detail choices in diagrams may affect student responses. Understanding what diagram affordances are present in a diagram, the context in which they are presented, and how those affordances might be perceived by students are all factors to take into consideration when choosing or designing diagrams for instruction.


76 pages




Northern Illinois University

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