Abstract: Program comprehension processes have previously been studied using methodologies such as think-aloud or comprehension summary analysis. Eye-tracking, however, has not been previously widely applied to studies of behavioral aspects of programming. We present a study in which program comprehension was investigated with a help of a remote eye-tracker. Novice and intermediate programmers used a program visualization tool to aid their comprehension while the location of fixations, fixation durations and attention switching between the areas of interest were recorded.In this paper 1) we propose an approach how to investigate trends in repeated-measures sparse-data of few cases captured by an eye-tracker and 2) using this technique, we characterize the development of program comprehension strategies during dynamic program visualization with help of eye-movement data.