HOW EXPERTS AND NOVICES EXPRESS SPATIAL THINKING IN SPEECH, GESTURE, AND ACTION IN COMPLETING A HYDROGEOLOGY TASK

Spatial reasoning and visualization skills are essential for practicing hydrogeologists since most subsurface processes are not directly observable. Practitioners must grapple with sparse and spatially discontinuous data from boreholes and wells to understand the dynamics of fluid flow and contaminant transport. Identifying specific spatial thinking skills important in hydrogeology is critical for improving hydrogeology curricula. To identify these skills, we conducted an expert-novice study in which 69 participants ranging from introductory hydrogeology students through seasoned professionals completed a demographic survey, four tests of spatial thinking skills, a hydrogeology knowledge test, and a contaminated site characterization task. The site characterization task involved completion of a geologic cross-section based on borehole data, contouring a potentiometric surface, a three-point problem, and contouring contaminant concentrations to delineate the extent of subsurface contamination and predict plume migration. Analysis of results with a linear regression model indicate that hydrogeology knowledge accounted for 33.5% of variance in performance on the site characterization task, with a composite of two spatial thinking skills (working within multiple frames of reference and visual penetrative ability) accounting for an additional 16.4% of the variance. To further explore how hydrogeology practitioners use spatial thinking skills, we videoed fifteen participants (experts and students) expressing their thought processes in verbal and non-verbal ways (e.g., gestures) as they completed the site characterization task. We coded the think-aloud data for instances of spatial reasoning by considering the combination of speech, spatial gestures, and spatial actions. For example, participants routinely used gestures to indicate the direction of groundwater flow and contaminant migration, and took actions to place site maps side-by-side to aid in matching well locations. Preliminary analysis suggests that there are different strategies, spatial actions, and thought processes used between high and low spatial thinkers and between expert and novice hydrogeologists.