# Collaborative Use of a Shared System Interface:
## 1 Introduction  
User gaze during interactions with information technologies (IT) has been the object of increasing interest in management research. Multiple research works in the field of human computer interaction (HCI) have investigated user's eye movements during system use (e.g., [PERSON] et al. [1]; [PERSON] et al. [2] ). In this regard, constructs related to IT user's gaze have been related with different information system (IS) -related constructs, including interest, attention, cognitive load, and confusion [3; 4; 5; 6]. Nevertheless, these studies have essentially focused on single-user settings. Consequently, even in the context of collaborative use, IT user's gaze indicators have been essentially recorded separately for each participant [7; 8]. Indeed, studies investigating simultaneous collaborative use of a shared interface are scant in the extant literature. Thus, the true role of users' gaze in this context of IT collaborative use is not well understood. Investigating gaze during collaborative use of shared system interfaces is important for several reasons. Firstly, gaze convergence of collectives of users, that is, the act of looking at the same location on a system interface, has been suggested to be important for group learning (e.g., [PERSON] et al. [2]) and group work (e.g., [PERSON] et al. [9]). Secondly, although most systems are designed with a single user in mind, they are frequently used in multiuser settings. Examples include individual productivity tools such as diagramming application [10] and e-commerce platforms [11]. To illustrate further, a recent study revealed that 53% of online household purchases are operated by multiple users shopping online together [12]. These multiuser settings involve users gazing at each other or at visual objects of interest in the system interface. Finally, during collaborative interactions, users may relate to IT artefacts visualized in the system interface. Indeed, users will navigate a given interface according to their own mental models, which can also be modified during navigation. Mental models are mental elaborations of user's understanding of knowledge and relationships between concepts or systems [13]. It is thus desirable that collaborating users have similar mental models regarding the system to facilitate collaboration. It has been suggested that mental model construction may be induced by eye movements, through which individuals learn spatial structure of visual elements (e.g., [PERSON] et al. [14]; [PERSON] et al. [15]). Hence, collaboration during joint interactions with system interface may be facilitated when user gazes are convergent. We investigated the eye movements of dyads of users during their collaborative use of a shared system interface. More precisely, we measured the extent to which the user dyads exhibited gaze convergence by looking at the same locations on the screen during system use. Moreover, we investigated the influence of gaze convergence on information system (IS) use-related constructs including cognitive states and task performance, raising the following research questions (RQ). RQ1: How can the degree of gaze convergence of a dyad collaborating simultaneously on a shared system interface be measured? RQ2: To what extent does gaze convergence relate to dyad cognitive states and dyad performance? The present study sought to answer these questions methodologically and theoretically. Firstly, we empirically illustrate feasibility of simultaneously and synchronously recording eye-tracking data of user dyads, a technique still embryonic in the HCI literature. Secondly, we propose a novel index for measuring gaze convergence (GC) of user dyads, a construct still scant in the literature. Finally, we examine the role of gaze convergence in relationship with system use-related constructs, one of the very few such initiatives in the literature. In the remainder of this paper, we test the dyad GC index and examine its validity through two consecutive studies. In the first study, we examine GC control validy.