Visualizing Competing Items over Time

Choosing between two or more alternatives, ranging from relatively simple alternatives to more complex ones, is a common and important task. Visualization techniques may help users to examine differences between such alternatives. The potential contribution of an adequate visualization may increase as the comparison becomes more complicated, when the compared alternatives include multiple dimensions, and when they are examined over time. We propose a novel visualization technique designed to represent the temporal evolution of multiple dimensions between two competitors at a glance. We exemplify how the visualization supports the comparison of two events according to their changes in eight discrete emotions over time. We report on a study that compared our suggested visualization with two common visualization techniques. User performance and preferences were measured under a formal task taxonomy, using Twitter data of real-world events. The experimental results indicate the effectiveness of our visualization as demonstrated by task completion time and accuracy.