Bound for (Certain) Sounds: Innate Cognitive and Emotional Auditory Predispositions in Domestic Chicks

Learning to sing, vocalise or react to different sounds is a crucial/important survival trait in all tetrapods. All of these abilities rest their foundations on auditory memories that guide the acoustic and vocal ontogeny in a large group of species. However, surprisingly little is known about the innate cognitive and emotional auditory predispositions that characterise animals from birth. Several studies have focused on the auditory behaviour of birds as a consequence of exposure to specific sound stimuli before or after hatching, thus ignoring natural behavioural and emotional responses that are not mediated by experimental manipulations of the developmental trajectories. To fill this knowledge gap, we have directed our attention on a species that represents an optimal model to investigate the existence of innate predispositions: the domestic chick (Gallus gallus domesticus). Using a head orienting paradigm and recording the latency to resume feeding as a behavioural response, we conducted a series of playback experiments on 3-day-old chicks, aimed at characterising their responses to sound samples ranging from conspecific vocalisations to musical timbres. The results showed an increase in the latency to resume feeding in response to those stimuli that are likely to be considered as negative, such as predator voices (e.g., dog barks), abrupt environmental sounds (e.g., thunder), and conspecific vocalisations expressing strong fear or those emitted by unknown adults. Our findings thus provide evidence for the existence of innate perceptual and emotional frameworks guiding auditory processing of vocal, environmental, and musical stimuli in a phylogenetically ancient bird species, suggesting that these traits may also be universal features of sound perception.