The rock-paper-scissors game in chimpanzees (Pan troglodytes)

Abstract

This study investigated the ability of chimpanzees (Pan troglodytes) to understand non-transitive relationships by training them in the rules of the Rock-Paper-Scissors (RPS) game. Seven chimpanzees were trained to perform a computer-controlled discrimination task. Each task used two figures, representing two of the three elements in each trial, which were completed in the following order: Paper-Rock sessions; Rock-Scissor sessions; Scissor-Paper sessions; and finally, mixed-pair sessions. The chimpanzees received a food reward every time they chose the correct figure. They had three sessions of 48 trials each day. On average, they received 339 training sessions. Four of the seven chimpanzees completed training. Three of them then received generalization tests using different stimuli with the same circular relationship, and one of the three passed the new task in 23 sessions. These results suggest that chimpanzees could learn about non-transitive relationships, and they are able to generalize this circular concept to new stimuli.