Cognitive Measurements of Graph Aesthetics

Abstract

A large class of diagrams can be informally characterized as node–link diagrams. Typically nodes represent entities, and links represent relationships between them. The discipline of graph drawing is concerned with methods for drawing abstract versions of such diagrams. At the foundation of the discipline are a set of graph aesthetics (rules for graph layout) that, it is assumed, will produce graphs that can be clearly understood. Examples of aesthetics include minimizing edge crossings and minimizing the sum of the lengths of the edges. However, with a few notable exceptions, these aesthetics are taken as axiomatic, and have not been empirically tested. We argue that human pattern perception can tell us much that is relevant to the study of graph aesthetics including providing a more detailed understanding of aesthetics and suggesting new ones. In particular, we find the importance of good continuity (ie keeping multi-edge paths as straight as possible) has been neglected. We introduce a methodology for evaluating the cognitive cost of graph aesthetics and we apply it to the task of finding the shortest paths in spring layout graphs. The results suggest that after the length of the path the two most important factors are continuity and edge crossings, and we provide cognitive cost estimates for these parameters. Another important factor is the number of branches emanating from nodes on the path.

An Empirical Review of the Connection Between Model Viewer Characteristics and the Comprehension of Conceptual Process Models

“…The variation was guided by well-known esthetic metrics from graph drawing research by Purchase et al (1997), Ware et al (2002), Purchase et al (2002), Petre (2006), and Purchase (2014): -Line crossings: An increase in the number of crossings has been found to decrease the readability of that layout. The models with good layout have no crossings while the bad layout ranges from 4 to 23 crossings.…”

On the Pragmatics of Model-Based Design

“…A major obstacle is the complexity and unclarity of this task. What are adequate aesthetic criteria for "appealing" diagrams [11,12,13]? Are there optimal solution algorithms or heuristics with acceptable results that adhere to the desired aesthetic criteria?…”

Toward Measuring Network Aesthetics Based on Symmetry

“…Several other measures of the aesthetics of networks or network-like structures have also been defined and studied (e.g., [11][12][13]). Moreover, Ware et al [13] review measures of graph aesthetics defined in [11], and in particular evaluate the cognitive cost to an observer of different visual representations.…”