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Geodashboards are often designed with explanatory elements guiding users. These elements (e.g. legends or annotations) need to be carefully designed to mitigate split attention or information integration issues. In this paper, we report expert interviews followed by a controlled experiment where we compare two interface designs with a focus on the split attention effect: (1) a multiple-legend layout with explanatory elements located next to each view, and (2) a single-legend layout with all explanatory elements gathered in one place. Different legend layouts did not affect the performance, but affected user satisfaction. 75% of the participants preferred the multiple-legend layout, and rated it with a higher usability score, mainly attributing this preference to the proximity of legend elements to the view of interest. Eye tracking data strongly and clearly verifies that participants indeed make use of the proximity: With the single-legend, the majority of eye-movement transitions were between the single-legend and the closest view to the legend, whereas with multiple-legend participants have shorter and more frequent legend visits, as well as more transitions between legends and views. Taken together, the design lesson we learned from this experiment can be summarized as ‘split the legend elements, but make it close to the explained elements’.

Proportional point symbols are commonly used in map displays. However, when such displays are zoomed out, the available map space shrinks and consequently symbols overlap and the display suffers from visual clutter. Therefore, solutions are needed to reduce visual clutter in zoomable map displays that contain proportional point symbols. The authors add to the body of knowledge through the investigation of the performance of three solutions: aggregation of unit areas, the displacement of overlapping symbols, and modified symbolization; four variations of modified symbolization are examined in detail. The original study begins with a consideration of the strengths and weaknesses of the solutions, with an emphasis on information loss. Thereafter, user sessions with 165 participants are arranged to gain empirical evidence of the performance of the solutions. The results reveal that although participants zoom out the map to zoom levels that implement visual clutter reduction techniques, they tend to zoom in the map and pan it to examine specific areas. Moreover, they willingly use the map with aggregated unit areas in cases when the solution facilitates task accomplishment. A certain amount of skepticism attaches to the solution that displaces overlapping symbols.

Geographic visualization tools with coordinated and multiple views (CMV) typically provide sets of visualization methods. Such configuration gives users the possibility of investigating data in various visual contexts; however, it can be confusing due to the multiplicity of visual components and interactive functions. We addressed this challenge and conducted an empirical study on how a CMV tool, consisting of a map, a parallel coordinate plot (PCP), and a table, is used to acquire information. We combined a task-based approach with eye-tracking and usability metrics since these methods provide comprehensive insights into users’ behaviour. Our empirical study revealed that the freedom to choose visualization components is appreciated by users. The individuals worked with all the available visualization methods and they often used more than one visualization method when executing tasks. Different views were used in different ways by various individuals, but in a similarly effective way. Even PCP, which is claimed to be problematic, was found to be a handy way of exploring data when accompanied by interactive functions. © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/),which permits non-commercial re-use, distribution, and reproduction in anymedium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.