Lateralised Social Learning in Chicks

Abstract

In social learning, one individual acquires information on objects encountered in the environment by observing the interaction of another individual with such objects. A highly adaptive form of social learning regards the biologically relevant features of food items. Functional lateralisation of the brain is a widespread phenomenon in the vertebrates, present both in social and non-social learning tasks (such as those involved in foraging activities). Here, we report on our recent studies on lateralisation in social learning following the observation of conspecifics’ behaviour. We employed the domestic chick as a model (since it is highly lateralized in many relevant tasks) and a social version of a passive avoidance learning (PAL) task in which one chick (the demonstrator) pecks at a bead whilst another chick (the observer) views the demonstrator’s response. The bead is either coated in a bitter-tasting substance or left dry. Later both chicks are presented with a similar, dry, bead to determine if learning has occurred. We demonstrated that chicks learn to avoid pecking by observation only of a conspecifics’ disgust reaction after pecking a bitter-tasting bead. This learning is lateralised: access to the right hemisphere is necessary for successful recall. This is in contrast to the non-social version of this task, in which the left hemisphere plays the dominant role, although both hemispheres are, in turn, subject to brief windows of “enhanced recall” during memory formation (as theorised by an influential model of memory formation, Andrew 1999). We also investigated whether such recall events are prevalent in the social learning task.