A User Study on Judging the Target Node in Partial Link Drawings

Partially drawn links are a possibility to reduce visual clutter in node-link visualizations of relational data caused by link crossings. Although partial links have some benefits concerning task performance, they exhibit issues regarding target node ambiguities. In this paper, we provide the results of a user study that investigates the performance in terms of task accuracy when judging target nodes to which partial links are pointing. We vary the link lengths and link directions as independent variables and measure the task accuracy as dependent variable while the exposure duration for each stimulus is fixed. The major result of our user study is that people tend to make more target node judgment errors with shorter link lengths. Moreover, the direction of the partial links also has an impact on the accuracy. With these results, we are able to choose appropriate parameter settings for graphs drawn with partial links. This can be regarded as a novel graph drawing criterion for improving the readability of graphs represented with partial links.