Lateralization of social learning in the domestic chick, Gallus gallus domesticus: learning to avoid

Abstract

Social learning occurs through the observation of conspecifics performing biologically relevant behaviours. Like other forms of learning, aptitude for such tasks may be influenced by cerebral lateralization. Social recognition is subject to lateralization and it seems highly likely that any lateralization effect would be transposed onto a social-learning situation. We used a social version of a passive avoidance task in which one chick (the demonstrator) pecked at a red bead while another chick (the observer) viewed the demonstrator's response. This bead was either coated in the bitter-tasting substance methylanthranilate (MeA) or was left dry. Thirty minutes later both chicks were presented with a similar, dry, bead to determine whether learning had taken place. Experiment 1 showed that chicks were able to learn, by observation only, not to peck the bead when it had been coated in MeA at training. Experiment 2 demonstrated a role of lateralization in performing the task; specifically, male observer chicks trained binocularly but tested monocularly had a poorer performance in this task with the left hemisphere than with the right. In experiment 3, we both trained and tested chicks monocularly. This time there was no difference between left-eyed and right-eyed chicks, suggesting a spontaneous bias for encoding relevant information available at training in the right hemisphere. In conclusion, chicks are able to avoid pecking just by observing a conspecific. The social learning appears to be lateralized to the right hemisphere in male chicks, females showing no bias in lateralization.