Cerebral and behavioural asymmetries in animal social recognition

Evidence is here summarized that animal species belonging to distant taxa show forms of social recognition, a sophisticated cognitive ability adaptive in most social interactions. The paper then proceeds to review evidence of functional lateralization for this cognitive ability. The main focus of this review is evidence obtained in domestic chickens, the animal model employed in the authors’ laboratories, but we also discuss comparisons with data from species ranging from fishes, amphibians and reptiles, to other birds and mammals. A consistent pattern emerges, pointing toward a right hemisphere dominance, in particular for discrimination of social companions and individual (or familiarity-based) recognition, whereas the left hemisphere could be specialized for “category-based” distinctions (e.g., conspecifics versus heterospecifics). This pattern of results is discussed in relation to a more general specialization and processing styles of the two sides of the brain, with the right hemisphere predisposed for developing a detailed, global and contextual representation of objects, and the left hemisphere predisposed for rapid assignment of a stimulus to a category, for processing releaser stimuli and for control of responses.