To see or not to see: visual contact, a primary need for social animals?

International audienceOne characteristic of sociality is the active seeking of proximity by conspecifics. Although active interactions and physical contacts can be involved, in many cases, visual contact at least plays an important role. In the present study, we investigated whether this motivation for visual contact is strong enough to become a “primary reinforcer”. Thus, we used an operant conditioning procedure to test whether isolated adult European starlings, a social species of birds, would actively trigger social or non-social stimuli presented as 2D pictures. The results show that true conditioning with no training and no other reward than the pictures is possible. Moreover, starlings expressed a preference for pictures of conspecifics over pictures of (1) landscapes and (2) monkeys. A mere picture can therefore act as a “primary reinforcer” in an operant conditioning procedure