Using ScanMatch scores to understand differences in eye movements between correct and incorrect solvers on physics problems

Using a ScanMatch algorithm we investigate scan path differences between subjects who answer physics problems correctly and incorrectly. This algorithm bins a saccade sequence spatially and temporally, recodes this information to create a sequence of letters representing fixation location, duration and order, and compares two sequences to generate a similarity score. We recorded eye movements of 24 individuals on six physics problems containing diagrams with areas consistent with a novice-like response and areas of high perceptual salience. We calculated average ScanMatch similarity scores comparing correct solvers to one another (C-C), incorrect solvers to one another (I-I), and correct solvers to incorrect solvers (C-I). We found statistically significant differences between the C-C and I-I comparisons on only one of the problems. This seems to imply that top down processes relying on incorrect domain knowledge, rather than bottom up processes driven by perceptual salience, determine the eye movements of incorrect solvers.