Mentally Visualizing Large Geologic Structures from Field Observations: A Behavioral Study
Kim A. Kastens and Toru Ishikawa
Lamont-Doherty Earth Observatory, Columbia University
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Artificial outcrops made of plywood that together would form a large geologic structure, part of which is eroded or covered by dirt and vegetation, are constructed on campus. One structure is an elongate basin, and another is an anticline. After walking around the outcrops, students are asked to choose among an array of scale models of possible geologic structures the one that they think best represents the buried structure. Then they orient the model so that it is aligned with the actual structure in the real world.
We ask expert geoscientists and novice learners to participate in this experiment. The novice learners are non-science majors at a local undergraduate college.
Skills and concepts that students must have mastered
Novice learners in this experiment are not required to have any specific geologic skills or concepts (experts are scientists and Ph.D. students at the Lamont-Doherty Earth Observatory).
How the activity is situated in the course
This activity is part of a series of NSF-funded behavioral experiments that aim to examine people's (expert geoscientists and novice learners) mental images of large geologic structures from field observations.
Content/concepts goals for this activity
As research investigators, we aim to examine
- how people mentally visualize large geologic structures (realistically scaled, three-dimensional, and mostly buried) from individual small pieces of information as outcrop observations;
- how students who have trouble with this task differ from successful students and expert geoscientsts, in terms of underlying spatial abilities, learning styles, and problem-solving strategies; and
- how such a skill can be trained. As research participants, students will become familiar with one aspect of what professional geologists do in the field.
Higher order thinking skills goals for this activity
Skills for three-dimensional spatial visualization, based on incomplete and separate information.
Other skills goals for this activity
To determine what is relevant to the task at hand and how to record the information for later use.
Description of the activity/assignment
We construct artificial outcrops out of plywood on the Lamont campus that together would form a large geologic structure, part of which is eroded or covered by dirt and vegetation. One structure is an elongate basin, and another is an anticline. Participants are expert geoscientists and novice learners. They will be guided by an experimenter around a set of outcrops and take notes while walking around. When they finished walking around the outcrops, they will be asked to choose among an array of scale models of possible geologic structures the one that they think best represents the buried structure. Then they will orient the model so that it is aligned with the actual structure in the real world. They will be asked to "think aloud" while choosing and orienting the model; this process is videotaped so that we can analyze their thought processes and develop strategy-training methods. As individual differences measures, they will also be asked to take standard spatial tests and a questionnaire assessing their learning style (verbal vs. spatial).
Determining whether students have met the goals
The scale models from which the participants will choose one are systematically varied on important properties, such as the ratio of the two axes, convexity/concavity, symmetry, dip of the rock surfaces, and so on, so that we can identify the nature of the participants' mental images in detail based on which model they choose. Together with the orientation of the chosen model with respect to the real-world structure, these behavioral responses will provide us with the participants' level of metric understanding of the structure. Furthermore, we will analyze the participants' notes and think-aloud protocols to seek further clues about their thought processes. Our preliminary data shows two clear patterns of the students' notes. Some students only wrote down words and focused on only individual outcrops (e.g., outcrop #1 is oval in shape, near a tree, in the sun); whereas some students took pictorial or graphic approaches (e.g., drew sketches or a map of the outcrops). Based on these data and individual differences measures, we will develop strategy-training methods that can be used to help troubled students master the field-based learning skills, which we ultimately aim to incorporate and assess in actual field-geology classes.
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