Recognition and Recall of Geographic Data In Cartograms

We investigate the memorability of two types of cartograms, both in terms of recognition of the visualization and recall of the data. A cartogram, or a value-by-area map, is a representation of a map in which geographic regions are modified to reflect a given statistic, such as population or income. Of the many different types of cartograms, the contiguous and Dorling types are among the most popular and most effective. With this in mind, we evaluate the memorability of these two cartogram types with a human-subjects study, using task-based experimental data and cartogram visualization tasks based on Bertin's map reading levels. In particular, our results indicate that Dorling cartograms are associated with better recall of general patterns and trends. This, together with additional significant differences between the two most popular cartogram types, has implications for the design and use of cartograms, in the context of memorability.