In an experimental situation called “diving for food”, groups of laboratory rats are tested in an aquarium where they have to dive and swim under water to reach the single source of food located at the other end. A behavioural differentiation appears: some rats — the carriers — dive to get food and others — non-carriers — stay in the cage and feed by stealing. We examine whether carrier and non-carrier profiles can be considered as social roles, defined as supraindividual features dependent on the social context. Carrier/non-carrier differentiation resulted in all groups tested. Individually tested, almost all rats can get food by diving and swimming. Differentiation also occurred in groups that had been previously trained alone in the device, and in groups whose members had all been carriers or non-carriers exclusively in a preliminary stage. As the access-to-food behaviour of a rat having to cope with the diving-for-food situation is settled by its social environment, we consider that the present experimental model is promising for the study of interactions between the individual and the social structure.