Figure 3. Mean frequencies of arousal behaviours of the victim during the prosocial phase.

There was a significant interaction between condition and species (p = 0.021) and a main effect of species (p = 0.001), but no main effect of condition (p = 0.859). Bonobos and chimpanzees showed more arousal behaviours in the prosocial phases of the Take and Give condition (each lasting 180 seconds) than orangutans and gorillas. However, only gorillas and bonobos displayed marginally more arousal in the prosocial phase of the Take condition compared to the Give condition. Error bars indicate SD.