Hemispheric specialization in spatial versus ordinal processing in the day-old domestic chick (Gallus gallus)

The intriguing similarity among species in representing numerosity in space from left to right may depend on a right hemisphere dominance in processing spatial information. We assessed the role of each hemisphere in spatial versus ordinal–numerical processing by testing chicks binocularly or monocularly. We showed that each hemisphere can process spatial plus numerical cues, but that selective use of numerical information requires the cooperation of both hemispheres.

Annals of the New York Academy of Sciences