Cooperative vocal output in common marmoset

Abstract

Besides our capacity for vocal imitation, the flexible motor control underlying vocal production is a hallmark of human communication. In the present study, we questioned if marmosets modulate their antiphonal vocal response in a strategic way that would facilitate communication by compensating for signal attenuation over distance. Using interactive playback software, we varied the amplitude of the stimuli to simulate a conspecific in distance (loud stimuli, soft stimuli) or in movement (looming stimuli, receding stimuli) and saw if marmosets make appropriate, strategic acoustic adjustments depending on the communication distance. Experiment 1 showed that marmosets increase their amplitude and call rate, and shorten the latency to respond upon hearing softer stimuli as opposed to louder stimuli. Experiment 2 showed that marmosets’ responses to receding stimuli and looming stimuli are not acoustically different. Our findings suggest that marmosets’ vocal production is flexible, cooperative and prosocial like human communication. Furthermore, such cooperative vocal output in marmosets seems more attributed to higher cognitive ability such as perspective taking rather than natural selection that promotes reproductive success.