Naïve chicks prefer hollow objects

Abstract

10Biological predispositions influence approach and avoid responses since the beginning of 11 life. Neonates of species that require parental care (e.g. human babies and chicks of the 12 domestic fowl) are attracted by stimuli associated with animate social partners, such as 13 face---like configurations, biological motion and self---propulsion. The property of being 14 filled is used as a cue of animacy by 8---month---old infants but it is not known whether this 15 reflects the effect of previous experience. We use chicks of the domestic fowl (Gallus 16 gallus) to investigate whether the property of being filled vs. hollow elicits spontaneous 17 or learned preferences. To this aim we tested preferences of naıve and imprinted chicks 18 for hollow and closed cylinders. Contrary to our expectations, we documented an 19 unlearned attraction for hollow stimuli. The preference for hollow stimuli decreased 20 when chicks were imprinted on filled stimuli but did not increase when chicks were 21 imprinted on hollow stimuli, suggesting that this feature is not crucial to categorize the 22 familiarity of imprinting objects. When chicks were imprinted on occluded stimuli that 23 could be either filled or hollow, the preference for hollow stimuli emerged again, 24showing that imprinting does not disrupt the spontaneous preference for hollow objects. 25. CC-BY-NC-ND 4.0 International license not peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was . http://dx.doi.org/10.1101/050799 doi: bioRxiv preprint first posted online Apr. 28, 2016; 2 Further experiments revealed that hollow objects were mainly attractive by means of 26 depth cues such as darker innards, more than as places to hide or as objects with high 27 contrast. Our findings point to predisposed preferences for hollow objects that might be 28 unrelated to social behaviour. 29 30

No evidence of spontaneous preference for slowly moving objects in visually naïve chicks

“…Decades of research on filial imprinting and the domestic chick have led to the discovery of many predispositions that help animals to orient toward specific stimuli features (sizes 20,21 , shapes 22 , colours [23][24][25][26] ). Furthermore, the predispositions described in precocial species such as the domestic chick are not only species-specific.…”

Sentience does not require “higher” cognition

“…More recently, imprinting has been used in young chicks and ducklings to study abstract thought, such as the concept of same/different (Versace et al, 2006;Martinho and Kacelnik, 2016) and statistical learning (Santolin et al, 2016). Similarities but also differences from the early cognition of humans have been observed (Versace et al, 2016) -the latter being no less important to a full understanding of the evolution of the mind.…”

A transient time window for early predispositions in newborn chicks

“…This phenomenon has been described in domestic chicks, that quickly develop affiliative responses towards the first objects they are exposed to (especially for moving objects), through the mechanism of filial imprinting [13][14][15][16] . Imprinting can also modulate predisposed responses 17 . While chicks are a convenient model to investigate early predispositions -because they are a precocial 18 species that can be easily tested in the absence of previous visual experience -human babies show striking similarities in the response to the stimuli preferentially attended and approached by chicks ( 6,(10)(11)(12)(19)(20)(21)(22)(23)(24)(25) ).…”