Can chicks discriminate between different rules?

It has been proposed that syntactic abilities of humans are based on processing repetitions and positional regularities. The simplest instantiations of syntactic rules with repetitions and positional differences are XYX and XXY. 7-month-old human infants were shown to be able to learn and discriminate these abstract rules and to generalize them to novel instances. These findings raise the question whether this competence is human specific or belongs to non-human animals, via a shared cognitive mechanism. Comparing human beings and songbirds, Chen et al. found that zebra finches could learn to discriminate the training stimuli but, differently from humans, they were not able to generalize to novel stimuli. We investigated whether newly hatched chicks of the domestic fowl (Gallus gallus) perform in the same way with XYX and XXY. Given the fact that newly hatched chicks promptly imprint on visual objects and subsequently approach those objects, we decided to imprint them on exemplars of these rules to investigate the capability to process the XYX and XXY patterns. To study whether a different way to present the stimuli might have an effect on their performances, we presented the stimuli in a simultaneous or serial configuration. Moreover to investigate the different involvement of the two hemispheres in processing these rules we tested some chicks monocularly.