TY - JOUR T1 - Naïve chicks prefer hollow objects JF - bioRxiv DO - 10.1101/050799 SP - 050799 AU - Elisabetta Versace AU - Jana Schill AU - Andrea Maria Nencini AU - Giorgio Vallortigara Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/04/28/050799.abstract N2 - Cognitive predispositions can influence approaching and avoid responses since the early stages of life. Young individuals of species that require parental care (e.g. human babies and chicks of the domestic fowl) are attracted by stimuli that contain features present in social partners such as face-like configurations, biological motion and self-propulsion. Studies on human infants showed that 8-month-old babies might possess expectations about the biological properties of animate entities. It is not clear though whether previous experience with animate entities had generated those expectations, or whether they arose spontaneously. We reasoned that naïve chicks of the domestic fowl (Gallus gallus) might be a convenient subject to investigate whether the mere property of being filled vs. hollow triggers unlearned preferences. To this aim we tested preferences of naïve and imprinted chicks for hollow and closed cylinders of the size and colour that elicit affiliative responses. We documented an unlearned attraction for hollow stimuli, showing that the property of being filled is not sufficient to elicit affiliative responses in chicks. The preference for hollow stimuli could be decreased through filial imprinting, by exposing naïve chicks to filled stimuli. When chicks were imprinted on stimuli that could be either filled or hollow, the preference for hollow stimuli emerged again. Further experiments revealed that hollow objects were mainly attractive by means of depth cues such as darker innards, more than as places to hide or as objects with high contrast. ER -