The introduction of play sessions in the routine management of great apes presents an important qualitative leap, since it includes an interaction between the keeper and the animal where the animal does not receive any physical compensation in the form of food, object or entertainment, is a purely emotional interaction where the keeper makes a playful behavior available to the animal, whose only reward is to create an empathetic, safe and relaxed environment that can have positive social repercussions within the group itself (Ávila, 2017; Cerdán , 2018; Pizzutto, Nichi, Ramiro, Ades and Alcindo, 2007; Adriaense, 2020). Conversely, a keeper-group interaction where there is competition for food or material enrichment could lead to higher levels of arousal and agonism, and a decrease in prosocial behaviors (Chelluri, Ross and Wagner, 2013). It is worth remembering that the targeted and systematic training of primates in general and great apes in particular is another way to positively reinforce their well-being (Perdue, 2018; Ward, 2013; Leeds 2016).

The hypothesis on which we will base our research is that the introduction of play sessions between the keeper and the social group in the daily management of gorillas entails changes within the group, favoring the sociability of the subjects, increased confidence and generation of a social dynamic that reduces potential sociability problems, increases affiliative behaviors and therefore increases levels of well-being. (Baker, 2004; Chelluri et al. , 2013; Manciocco, Chiaroti and Vitale, , 2009).