Perceptual Characteristics of Computerized Program Visualizations can Differentially Affect Detection and Localization Performance

Abstract

Program visualizations (PVs) are sometimes less effective in teaching computer algorithms than desired. One reason may be that PV designers have largely ignored the users' perceptual capabilities. We examined perceptual characteristics of bar displays, similar to those used in teaching sorting algorithms. Within each experimental condition we varied the number of bars displayed, number of flashing cues, number of bars changing height, and whether bars were labeled. Across experimental conditions we examined placement of bars within the visual field and whether bar profiles were fixed or varied from trial to trial. Thirty-six university students participated. Bars placed in peripheral locations can harm performance because of human retinal eccentricity effects. Moreover, many perceptual characteristics that help localization of critical changes (e.g., labels and cues) do not help detection, whereas some that help detection (e.g., 2 simultaneous changes) hurt localization. Our results suggest that consideration of both users' perceptual capabilities and tasks may improve effectiveness of PVs.

The importance of interactive questioning techniques in the comprehension of algorithm animations

“…The prior two experiments examined perceptual features. In the first, we looked at the effect of cueing on the user's ability to detect and locate object transformations [Davis et al 2006], and the second focused on the overall comprehension of an algorithm when these cueing techniques were used in the AA [Reed 2006]. The purpose of this study is to analyze the usefulness of varying types of pop-up questions that pause the animation and require users to interact with the system by responding to questions before the animation resumes.…”