The usability of task modeling tools

User interface modeling tools can play a useful role for engineering interactive systems. However, little is known about how these tools are used, the strategies and workarounds employed, and whether usability problems are encountered. To start answering this question, we run a user study with software engineers carrying out task modeling activities. The analysis of the data generated by an instrumented CTTE and an eye-tracker uncovers five workflows that illustrate how the task model hierarchy is populated and edited, operators are added to tasks, and when model consistency is checked. These findings inform design implications for task modeling tools and formulate hypotheses for future work.