Division of vocal signaling in cooperating marmoset dyads

Abstract

Communication enables partners to coordinate actions toward shared goals, but how vocal communication is organized during cooperation remains poorly understood. We recorded vocalizations from three common marmoset (Callithrix jacchus) dyads as they learned a mutual cooperation task requiring coordinated lever pulls for reward. Vocal behavior was divided by social hierarchy: dominants produced t-peeps, whereas subordinates produced chirps. Interestingly, dominant t-peeps followed failed cooperative pulls, peaked when cooperative bouts broke down, and declined after learning. By contrast, subordinate chirps followed successful pulls, accumulated during sustained cooperation, and persisted after learning. Each call was linked to the task role of the caller: dominant animals t-peeped more in sessions they led, and subordinates chirped mainly after cooperations they initiated, associations that sharpened with learning. Thus, social rank determined which vocal signal a partner used, whereas task role and the state of cooperation determined when to communicate. These complementary vocal signals of failure and success reveal how hierarchy, task role and task phase organize communication during joint action in cooperating marmosets.