Detour behaviour, imprinting and visual lateralization in the domestic chick

Detour behaviour was studied in chicks faced with a vertical-bar barrier be hind where an imprinting object (a red ball) was located. Right-eyed chicks took less time to detour the barrier than left-eyed chicks, and binocular chicks showed a bias to detour the barrier on the left side, thus maintaini ng visual contact with the imprinting object using the lateral field of the right eye, while circling around the barrier. In males, the asymmetries we re consistent all along the first two weeks of Life, whereas in females the y disappeared on days 8 and ii. When tested with a slightly novel version o f the original imprinting object (i.e., a ball of a different color), binoc ular chicks showed a bias to detour the barrier on the right side, thus sho wing preferential use of the left eye. The same bias occurred when unfamili ar conspecifics were used as goal-objects. Results suggest that cerebral la teralization in birds can directly affect visually-guided motor responses t hrough selective use of the lateral field of vision of the eye contralatera l to the hemisphere which has to be put in charge of control of overt behav iour. (C) 1999 Elsevier Science B.V. All rights reserved.