  Collaborative robots (cobots) are widely used in industrial applications, yet
extensive research is still needed to enhance human-robot collaborations and
operator experience. A potential approach to improve the collaboration
experience involves adapting cobot behavior based on natural cues from the
operator. Inspired by the literature on human-human interactions, we conducted
a wizard-of-oz study to examine whether a gaze towards the cobot can serve as a
trigger for initiating joint activities in collaborative sessions. In this
study, 37 participants engaged in an assembly task while their gaze behavior
was analyzed. We employ a gaze-based attention recognition model to identify
when the participants look at the cobot. Our results indicate that in most
cases (84.88\%), the joint activity is preceded by a gaze towards the cobot.
Furthermore, during the entire assembly cycle, the participants tend to look at
the cobot around the time of the joint activity. To the best of our knowledge,
this is the first study to analyze the natural gaze behavior of participants
working on a joint activity with a robot during a collaborative assembly task.
