We describe an experiment that evaluates the effect of two attributes of an algorithm animation: presence of cueing (flashing) to indicate to the viewer that two data elements have been compared, and type of animation (arcing move or grow/shrink) to indicate that two data elements have exchanged values. We evaluate the impact of these attributes both on perception of the animated changes and on viewer comprehension of the depicted algorithm, as measured by the number of correctly answered questions in two question sets: "traditional" (comprehension) questions and "popup" (perception) questions. No significant effect on comprehension was observed for either flash cueing or exchange motion, though we note that comparison and exchange behaviors were redundantly cued in the animation studied. Signficant effects were found for flash cueing and "move" versus "grow" in the perceptual questions displayed in popup windows.
The VizEval Suite * is an environment designed to support experimentation with and evaluation of program visualization attributes that affect the user's ability to grasp essential concepts. In this paper, we describe the VizEval Suite and an initial experiment conducted both as a test-bed of the VizEval Suite and to study how perceptual/cognitive characteristics of the visualization affect the users' understanding of the program visualization. VizEval is designed to simplify the creation and analysis of such studies. Our experimental results show that some perceptual/cognitive characteristics that help one task (e.g., detection of critical information) may harm another (e.g., localization of critical items), and vice versa. The VizEval software is available for download at
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.
We examined two means of reducing uncertainty in visual search: 1) visual-relatedness of a prime to a target and 2) expectancy (based on the proportion of validly primed trials). The two processes were decoupled using a short and a long inter-stimulus interval to examine their respective time courses in visual search. Twelve participants engaged in a discrimination task and a visual search task. The obtained results suggest that visual-relatedness affects search performance early, but its effects rapidly decay. They also suggest that expectancy requires time to accrue before it can affect visual search performance, but its effects are more long lasting than visual-relatedness. These results offer guidance for designing visual displays. In tasks that require split-second decisions designers should be encouraged to prime visualrelatedness. Moreover if the onset of the display and the required decision are separated by a longer interval, displays should inform users of likely outcomes (i.e. manipulate user's expectations).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.