Performance in a Collaborative Search Task: The Role of Feedback and Alignment.

When people communicate, they coordinate a wide range of linguistic and non-linguistic behaviors. This process of coordination is called alignment, and it is assumed to be fundamental to successful communication. In this paper, we question this assumption and investigate whether disalignment is a more successful strategy in some cases. More specifically, we hypothesize that alignment correlates with task success only when communication is interactive. We present results from a spot-the-difference task in which dyads of interlocutors have to decide whether they are viewing the same scene or not. Interactivity was manipulated in three conditions by increasing the amount of information shared between interlocutors (no exchange of feedback, minimal feedback, full dialogue). We use recurrence quantification analysis to measure the alignment between the scan-patterns of the interlocutors. We found that interlocutors who could not exchange feedback aligned their gaze more, and that increased gaze alignment correlated with decreased task success in this case. When feedback was possible, in contrast, interlocutors utilized it to better organize their joint search strategy by diversifying visual attention. This is evidenced by reduced overall alignment in the minimal feedback and full dialogue conditions. However, only the dyads engaged in a full dialogue increased their gaze alignment over time to achieve successful performances. These results suggest that alignment per se does not imply communicative success, as most models of dialogue assume. Rather, the effect of alignment depends on the type of alignment, on the goals of the task, and on the presence of feedback. Cooperation among people is often mediated by verbal communication, and removing this channel of communication changes the context of cooperation. Coco, Dale, and Keller report evidence that dyadic visual search is better when dyads diversify their eye movements, particularly when they cannot rely on verbal communication to coordinate. Results demonstrate how perceptual and cognitive tasks can require more complex forms of coordination than synchronization and alignment.