International Journal of Comparative Psychology

This study examined turn taking by adult and infant cross-fostered chimpanzees in one-on-one signed conversations with a human. The study identified turns as alternating, overlapping, or simultaneousand explored the timing of overlapping turn initiations in detail for both age groups. Adult chimpanzee turn taking was furthermore examined in two conditions; in the first condition the human responded to the chimpanzees with scripted probes and in the second condition the human signed freely. Results showed that the adult chimpanzees engaged in more alternating turns in the scripted condition and more overlapping turns in unscripted condition. In the interactions of the unscripted condition, the adult chimpanzees and the human partner initiated overlapping turns with nearly equal frequency, and the chimpanzees were likely to initiate overlap as the partner completed a turn. In comparable unscripted interactions, the infant chimpanzees initiated significantly more overlap thantheir partners and initiated overlap randomly throughout the partner’s sign. Results suggest that turntaking in the chimpanzees developed with experience.