Is the brain of animals and humans naturally wired to recognize faces? Is there an innate biological mechanism that explains this ability? Questions that like these have been fuelling a debate that involves, on the opposite side, those who believe that face recognition is a skill that can be learned through experience and exposure to faces and those who believe that it is innately predisposed in the brain. A recent study by a research team of the Center for Mind and Brain Sciences (CIMEC) of the University of Trento has given a contribution to the debate. The team identified, in one-week-old chicks that have never been exposed to faces, a population of neurons that respond to a face-like stimulus composed of three dots that resemble two eyes and a beak (or a mouth). The animals do not respond to isolated facial features or to dots that are arranged in a disordered manner and that do not recall facial features. The results suggest that face recognition is therefore innate.
The study has been published in PNAS.
About the study. Numerous behavioural studies suggest that face selectivity may be an innate ability of the brain. Both human newborns and newly hatched chicks who have never seen faces before show spontaneous attraction to face-like stimuli composed of three dark features representing eyes and a mouth (or a beak). However, the neural mechanism of this innate predisposition was unknown.
Experiments conducted by the research team of UniTrento have shown that baby chicks respond to shapes that resemble schematized faces. The response was identified in a population of neurons in a specific area of the brain. It is called the 'caudolateral nidopallium' and is considered an avian equivalent of the mammalian prefrontal cortex.
The study was conducted in the Animal Cognition and Neuroscience (ACN) Laboratory at Cimec, directed by Giorgio Vallortigara, who explains:«We performed a series of control experiments using schematic faces in which the features were shuffled, displaced, or arranged in all possible combinations. And these neurons seem to respond only to faces. This suggests that this sensitivity to faces is probably innate in the brains of vertebrates».
Another interesting aspect of the research is the function of this sensitivity, which explains, for example, why sometimes we see faces in the clouds or in spots on the walls, a phenomenon that is known as "pareidolia". «This psychological process – says Vallortigara – is the result of a specific brain mechanism. Our brains are naturally wired to respond to this very simple configuration of dots arranged in the right positions. These are stimuli that do not exist in nature. There are no schematic faces in the world, but these platonic faces are the simplest way for brains to represent something that looks like a face. So, a newborn baby or a newborn chick will be attracted by these stimuli consisting of three dark spots arranged in an inverted triangle and thus will be able to learn, over time, the specific characteristics of the mother's face and distinguish them from those of a stranger. These neurons act as a kind of face detector, a mechanism that facilitates learning about a particular category of stimuli, which is important from the point of view of social life».
New scenarios for theories on learning. The study suggests that learning would not be possible if it were not supported by predisposed innate mechanisms. According to the authors of the study, learning from experience, through trials and errors, would take too long and with high risk of making mistakes.
About the article
The first author of "Innate face-selectivity in the brain of young domestic chicks" is Dmitry Kobylkov. Other contributors are Orsola Rosa-Salva and Mirko Zanon, who have been supervised by Giorgio Vallortigara. The research has received European funding through Professor Vallortigara's ERC Advanced grant Spanumbra.
The article was published in PNAS magazine and can be found at www.pnas.org/doi/10.1073/pnas.2410404121
