Hemispheric processing of landmark and geometric information in male and female domestic chicks ( Gallus gallus)

Abstract

A place learning paradigm was used to assess lateralisation and sex differences in domestic chicks dealing with global (geometric shape) and local (identity of a beacon) aspects of spatial encoding. Male and female domestic chicks were trained binocularly to localise food buried under sawdust in the centre of a square-shaped enclosure. They were then tested binocularly and monocularly (Experiment 1). Training in the same task was also carried out in the presence of a centrally placed visual beacon, so that chicks could then be tested in a number of transformed versions of the training arrangement: after removing the beacon (Experiment 2), after shifting the beacon to a corner (Experiment 3) and after simultaneously shifting the beacon to a corner and replacing it with a second, visually different, beacon (Experiment 4). Results show that the right hemisphere prevalently attends to the geometry of the environment in both male and female chicks. Males rely upon local information (beacon) more than females, also showing stronger encoding of this information in their left hemisphere than their right hemisphere.