The ability to identify and retain logical relations between stimuli and apply them to novel stimuli is known as relational concept learning. This has been demonstrated in a few animal species after extensive reinforcement training, and it reveals the brain’s ability to deal with abstract properties. Here we show relational concept learning in newborn ducklings without reinforced training. Newly hatched domesticated mallards briefly exposed to a pair of objects that were either the same or different in shape or colour later preferred to follow pairs of new objects exhibiting the imprinted relation. Thus, even in a seemingly rigid and very rapid form of learning like filial imprinting, the brain operates with abstract, conceptual reasoning, a faculty often assumed to be reserved to highly intelligent organisms.
