Filial imprinting and social predispositions in chicks (Gallus gallus domesticus)

The domestic chick became a model for understanding memory, learning and the onset of social behaviours. Just after hatching and for a limited period, the naïve bird seeks a suitable object to imprint. Thanks to laboratory studies, the filial imprinting has been well documented in the very first few hours. However, how the filial imprinting preferences develop and evolve over time remained relatively unexplored. Therefore, we built an automated setup allowing us to follow the animal behaviour across prolonged durations and investigate the stability and variability of filial imprinting preferences. We demonstrated that three days of exposure to artificial objects produce lasting and robust imprinting preferences. With lower imprinting duration, we found that the animal predispositions strongly influence the filial imprinting preferences. Those social predispositions guide the domestic chicks towards living creatures – or at least, towards stimuli conveying animacy. To complete this general pattern, we performed two experiments manipulating motion dynamics. We showed that chicks prefer quickly rotating objects and agents moving with unpredictable temporal sequences: two cues probably used to detect living animals' presence. Both imprinting and social predispositions influence each other, but whether they share a neurophysiological ground was yet to be described. Such as for filial imprinting, we showed that the thyroid hormone T3 strongly affects the sensitive period for animacy preference. T3-inhibition closes the sensitive period for animacy preference and T3-injections re-opens it. Altogether, the present thesis complete previous research on filial imprinting and social predispositions: two distinct but interconnected mechanisms that can help to better understand the mind foundations at the onset of life.