Learning abstract rules in an animal model (Gallus gallus): experimental evidence in social and non-social contexts.

Sequence learning allows the encoding of the properties of event sequences, discriminating series composed of items presented in altered order (e.g., ABA, AAB), while rule learning allows the recognition of a familiar structure underlying a sequence, even when composed of perceptually unfamiliar items. Human infants rapidly encode serial order in event sequences, recognizing and generalizing abstract algebraic-like patterns. These abilities might be crucial for language development but they seem to be not specific to linguistic domain. Moreover, sequence and rule learning have been discovered also in non-human animals, in line with an adaptive role of these mechanisms in a variety of sophisticate non-linguistic cognitive operations. In the present study, we imprinted naïve newborn chicks on a sequence of arbitrary visual elements (e.g., geometric shapes ordered according to an ABA rule, creating sequences such as cross-circle-cross). Afterward, we tested chicks’ choice between this familiar sequence and a structurally different one, composed of the same elements in altered order (e.g., AAB, cross-cross-circle). We also tested chicks’ ability to generalize the structure of the sequence they have learnt to sequences composed of novel elements (unfamiliar geometric shapes). Chicks successfully generalized, showing preferential approach of the perceptually-novel sequence whose structure resembled that of the imprinting stimulus. In a further experiment we extended our initial results, investigating whether this same generalization ability can be revealed also in a non-social context, employing a learning paradigm in which chicks are trained to find food hidden behind screens depicting one type of sequence.