Developing a process model for visual penetrative ability
Visual penetrative ability (VPA) is a basic skill for any geology undergraduate student and is also required in many introductory laboratory exercises designed for nonmajors. This is the ability to visualize the three-dimensional (3-D) underground structure of folded sedimentary rocks from two-dimensional (2-D) surface clues. This study seeks to understand the origins of difficulties that introductory geology students encounter with this task. Problem-solving interviews were conducted with students representing the range of performance on the GeoSAT, a semiquantitative instrument designed to measure VPA. We conducted think-aloud, discursive interviews where participants solved similar 3-D visualization tasks. The interviewers interacted with participants to probe their problem-solving difficulties and thought processes while they were working. Analysis of interviews and videotapes of student gestures yielded insight into the nature of the difficulties faced by students in solving this style of spatial problem, and explained the origin of many of the common incorrect responses seen by previous workers using the GeoSAT. Students with high VPA appear to rapidly construct a 3-D internal visual model, and readily produced gestures and physical expressions illustrating their spatial understanding. Students with poor VPA tend to view external information as merely a type of “gift wrapping” over the cubic volume and do not perceive the internal structure. They also do not typically address spatial concepts through physical expression. We construct a process model for VPA that describes the origin of commonly observed errors at crucial steps, and associated accommodation strategies used by students struggling with spatial visualization of this type.