Do chimpanzees make sure others can see what they are doing when they need to cooperate? (#890)
Chimpanzees (Pan troglodytes) cooperate with group members in a variety of ways, such as group hunting and boundary patrolling. In order to do this successfully they need to coordinate their actions with others and one possible way to coordinate is to use communication (such as gestures and vocalisations). However, previous experimental studies with captive chimpanzees suggest that communication does not play a significant role in coordinating their actions. Therefore we were interested in alternative strategies chimpanzees may be using to coordinate; namely, whether chimpanzees take into account what their cooperative partners can see and use this to aid coordination (an ability they have demonstrated in studies using competitive paradigms). To address this question we presented captive chimpanzees with a pure coordination problem. In order to access food rewards two individuals were required to choose the same one of four options. The decisions of the two individuals were made sequentially so that the second individual could respond to the decision of the first (and thus release rewards for both of them). In the test situation a barrier blocked visual access to two of the options for the responder (but not the initiator). Thus, to be certain of success, the initiator should make their choice visible to the responder. We contrast this with a competitive version, in which the responder can steal from the initiator. In this case we would expect the initiator to hide their decisions to reduce the possibility of stealing by the responder. The results of this study will be discussed in relation to the mechanisms underlying cooperative behaviour in chimpanzees.