HOW A GEOLOGIST CAN GET LEAD ASTRAY: A VIDEO LOG STUDY EXAMINING HOW ERRORS IN OBSERVATIONS AND INTERPRETATIONS YIELD ERRORS IN GEOLOGIC MAPS
The participants mapped a field area for which there exists a consensus understanding of the underlying geology (i.e., an “answer key”). In addition to a head-mounted camera, participants also wore a GPS unit to record their position throughout the day. Both the GPS data and video logs are time-stamped, enabling the data sets to be synchronized. The videos were coded both for instances of visible actions (e.g., measuring strike and dip, breaking a rock sample for a fresh surface, or testing a rock sample with HCl) and for themes in spoken thoughts (e.g., procedural and declarative knowledge, reasoning, or metacognition).
From analyses of the video logs, we find that for the two novices, data collection drives model development. The differences in the accuracy of their maps are determined more by their interpretations of the data. Both experts use an aerial photograph of the field area to propose an initial interpretation of the underlying geology; their initial interpretations guide later data collection and model refinement. The difference in the accuracy of their maps reflects the differences in their initial interpretations and subsequent model development.