Marmoset Monkey Call Duration and the Influence of Initial Calls on Response Calls in Paired Vocal Scenarios

Abstract

In some species, vocalization represents a vital asset for survival and forging connections with other individuals. Humans and marmosets both participate in a vocal ritual known as turn taking, thereby allowing the marmoset to serve as a compelling model system for human speech. The coupled oscillator model, proposed in a previous study, uses inter-call intervals to explain how marmosets time their vocalizations to avoid overlap in paired scenarios. In this study, I turn my attention to an understudied parameter of marmoset vocalizations; call duration, in the hope of simultaneously rationalizing a confounding result present in developmental data, and illuminating the role of call duration itself within the context of this oscillator model. In my statistical analysis of “alone” and “paired” marmoset data collected from a previous study, I uncovered a significant, positive relationship between initial and response call duration. I also designed a playback experiment to isolate this relationship specifically, but no response vocalizations from the subjects emerged. Despite this, my experimental design provides a template for future studies aiming to investigate the relationship between initial and response call duration. Additionally, the result I uncovered in my data analysis suggests that marmosets use call duration in a similar manner that inter-call intervals are used in the coupled oscillator model: to prevent vocal overlap. Since eschewing interruptions during a vocal exchange is a crucial part of human speech, this study more generally provides insight into the intricacies of human vocalization timing.