Chicks discriminate human gaze with their right hemisphere

Domestic chicks were tested for eye use while feeding on the floor in the presence of a dummy mask which could either look at the location where the chicks were feeding or in the opposite direction. Animals completely naïve of visual experience of human eyes and gaze showed a more intense fear response when directly looked at (as shown by higher latency to approach the food) and a preferential use of the left eye (mainly feeding structures in their right hemisphere) to monitor the dummy mask. This response, seemingly predisposed, could be reversed in chicks with experience of human eyes and gaze directed toward them, which showed higher latency to approach the food and preferential left eye use when the dummy mask looked away from them. The results are discussed in relation to evidence for a right hemisphere involvement in fear responses and detection of predators in the vertebrate brain.