Task goals constrain the alignment in eye-movements and speech during interpersonal coordination

Collaborative task performance is assumed to benefit from interpersonal coordination between interacting individuals. Prominent views of language use and social behavior, including the Interactive Alignment Model (IAM; Pickering & Garrod, 2004), support this view by building on tasks that require monitoring a partner’s perspective (e.g., in route planning), proposing that behavioral alignment enables conceptual convergence. However, the role of alignment in tasks requiring complementarity (e.g., a “divide and conquer” strategy during joint visual search) remains underexplored. We address this gap by manipulating task goals (route planning vs. visual search) as forty dyads completed ten trials involving subway maps while their eye movements and speech were co-registered. We used Cross Recurrence Quantification Analysis (CRQA) to examine the temporal relationships between partners’ eye fixations and word sequences, generating measures that reveal similarity and dynamic coupling. Dyads exhibited more gaze alignment in route planning than visual search across a range of CRQA metrics. Gaze alignment also varied across the trial and related differently to accuracy: in visual search, greater alignment late in the trial predicted better performance. In speech, route planning prompted longer and more entropic word sequences, but lower overall recurrence than visual search. This finding suggests that the two modalities organize in a compensatory fashion to support distinct task demands. These results support a theoretical framework more general than IAM, in which interactive alignment emerges as a consequence of dynamic adaptation to task goals. Overall, task goals constrain how people coordinate behavior and offer insights into how collaborating partners distribute their multimodal contributions.