  A wide variety of use case templates supports different variants to link a
use case with its associated requirements. Regardless of the linking, a reader
must process the related information simultaneously to understand them. Linking
variants are intended to cause a specific reading behavior in which a reader
interrelates a use case and its associated requirements. Due to the effort to
create and maintain links, we investigated the impact of different linking
variants on the reading behavior in terms of visual effort and the intended way
of interrelating both artifacts. We designed an eye tracking study about
reading a use case and requirements. We conducted the study twice each with 15
subjects as a baseline experiment and as a repetition. The results of the
baseline experiment, its repetition, and their joint analysis are consistent.
All investigated linking variants cause comparable visual effort. In all cases,
reading the single artifacts one after the other is the most frequently
occurring behavior. Only links embedded in the fields of a use case description
significantly increase the readers' efforts to interrelate both artifacts. None
of the investigated linking variants impedes reading a use case and
requirements. However, only the most detailed linking variant causes readers to
process related information simultaneously.
