Volitional spatial attention is lateralized in crows

Like humans and many other animal species, birds exhibit left-right asymmetries in certain behaviours due to differences in hemispheric brain functions. While the lateralization of sensory and motor functions is well established in birds, the potential lateralization of high-level executive control functions, such as volitional attention, remains unknown. Here, we demonstrate that carrion crows exhibit more pronounced volitional (endogenous) attention for stimuli monocularly viewed with the left eye and thus in the left visual hemifield. We trained four crows on Posner-like spatial cueing tasks using informative cues to evaluate their volitional top-down attention. The crows detected cued targets using either the left or right eye. As a measure of volitional attention, we calculated reaction time differences for detecting targets that were correctly (validly) and incorrectly (invalidly) cued, separately for the left and right visual hemifields. We found that cued targets were detected more quickly and efficiently in the left visual field compared with the right visual field. Because the left-eye system of the crow's brain processes information primarily from the left visual hemifield, these findings suggest that crows, like humans, exhibit superior executive control of attention in the left-eye/right hemisphere system of their brains.