Investigating Mechanisms for Ensemble Visualization Interpretation: The Influence of Proximity, Contact, Density, and Spread on Judgments of Risk

Cone of Uncertainty (COU) visualizations are commonly used to convey to the public the uncertain forecast path of an approaching hurricane. However, the cone’s edge causes a precipitous drop in the sense of risk for locations beyond the cone, where no such discontinuity truly exists. An alternative approach using visual ensembles—Animated Risk Trajectories (ARTs)—can overcome this containment effect. However, the mechanism underlying resulting judgments of risk have not been explored. The current study used four different features within ARTs to examine which dimensions contribute to a sense of risk at a target location. Replicating prior findings, ARTs showed a gradual change in judgments of risk with increasing eccentricity from the single most likely storm path, whereas COUs showed a steep decline outside the cone. For ARTs, instances of potential storm paths passing just inside (proximity) or outside (spread) a location did not influence judgments of risk. An instance intersecting a location increased perception of risk (contact), but a larger impact was seen from the presence of a number of instances (density) around the location. Implication of these findings for designing visualizations to elicit a commensurate sense of risk are discussed.