An Eye Tracking Study into the Effects of Graph Layout

TL;DR

This eye tracking study investigates how crossing angles and geometric-path tendencies in graph layouts affect reading performance, revealing that small crossing angles slow down path searches but crossings minimally impact node locating.

Contribution

It provides initial empirical insights into how crossing angles and geometric-path tendencies influence graph reading, addressing a gap in understanding graph readability with crossings.

Findings

Small crossing angles slow down path search tasks.

Crossings have little effect on node locating tasks.

Geometric-path tendency affects path-following difficulty.

Abstract

Graphs are typically visualized as node-link diagrams. Although there is a fair amount of research focusing on crossing minimization to improve readability, little attention has been paid on how to handle crossings when they are an essential part of the final visualizations. This requires us to understand how people read graphs and how crossings affect reading performance. As an initial step to this end, a preliminary eye tracking experiment was conducted. The specific purpose of this experiment was to test the effects of crossing angles and geometric-path tendency on eye movements and performance. Sixteen subjects performed both path search and node locating tasks with six drawings. The results showed that small angles can slow down and trigger extra eye movements, causing delays for path search tasks, whereas crossings have little impact on node locating tasks. Geometric-path tendency indicates that a path between two nodes can become harder to follow when many branches of the path go toward the target node. The insights obtained are discussed with a view to further confirmation in future work.