– “It’s there on the table.” … – “Where, here ?”
– “No no, to the left.” … – “I don’t see it.”
– “Right there under the napkin.” … – “Ahhhhh I got it.”
The situations in which one individual communicates an information to another and persists until the other shows signs of having acquired the information are referred to as communicative persistence. The phenomenon is believed to be important as many social signals are actually accidental. For instance, you might “communicate” that you know the position of an object by looking in that direction without necessarily wanting to communicate. Communicative persistence can be regarded as evidence that the social signal is intended and not accidental. This is at least the argument presented by the authors of a recent study published in Animal Cognition by Anna Ilona Roberts and colleagues1.
The study looked at a series of gestures that chimpanzees use to influence the behaviors of others. For instance, extending a limb is usually followed by another chimpanzee grooming the limb. Backward sweeping is often followed by another climbing on the signaller’s back. We don’t necessarily know what the meaning of each of these signals are but we know a great deal about what other chimpanzees do in response.
The main result of the study is that when the expected response is not produced by the nearby chimpanzee, the signaler is more likely to repeat the signal, whereas when the expected response is produced by the partner, the gesture is much less likely to be repeated. The data gathered by the experimenters consists of bouts of 20 minutes of video recording following one of twelve wild chimpanzees for a total of 250 hours of video.
This study is an important one because it provides systematic and clear evidence that chimpanzees do show some degree of communicative persistence. The study is a good first step and further works might allow us to understand better the social contexts in which communicative persistence occurs in chimpanzees.
1. Roberts AI, Vick SJ, Buchanan-Smith HM. (2013) Communicative intentions in wild chimpanzees: persistence and elaboration in gestural signalling. Animal Cognition 16:187-96.