Spatial alignment facilitates visual comparison.

Humans have a uniquely sophisticated ability to see past superficial features and to understand the relational structure of the world around us. This ability often requires that we compare structures, finding commonalities and differences across visual depictions that are arranged in space, such as maps, graphs, or diagrams. Although such visual comparison of relational structures is ubiquitous in classrooms, textbooks, and news media, surprisingly little is known about how to facilitate this process. Here we suggest a new principle of spatial alignment, whereby visual comparison is substantially more efficient when visuals are placed perpendicular to their structural axes, such that the matching components of the visuals are in direct alignment. In four experiments, this direct alignment led to faster and more accurate comparison than other placements of the same patterns. We discuss the spatial alignment principle in connection to broader work on relational comparison and describe its implications for design and instruction. (PsycInfo Database Record (c) 2020 APA, all rights reserved) Public Significance Statement—This research reveals that the way in which visuals are placed on the page or screen influences the efficiency by which people can identify similarities and differences between the visuals. Arranging visuals such that their corresponding components can be readily aligned optimizes the efficiency of visual comparison. (PsycInfo Database Record (c) 2020 APA, all rights reserved)