Functional performance of the visual system in dogs and humans: A comparative perspective

Vision in dogs is generally considered poor compared with humans, and recent reports have reviewed some of the physiological principles underpinning dog vision, but a systematic comparison of the physiological and neurobiological features of vision in dogs compared with humans appears to be lacking. This means there is a risk of an anthropocentric perspective of the topic rather than an understanding grounded in a wider biological context. It is also important to appreciate that deficits in one aspect may be compensated for in other parts of the visual system, so generalizing about performance on the basis of a single feature within the visual system might be misleading. This review provides an overview of the visual perceptual abilities of dogs versus humans, grounded in the visual system's physical structures (see supplementary information) for detecting different visual features of the environment through to its initial processing prior to its cognitive evaluation. Differences and variations that exist between dogs and humans and why these might occur are considered, by reference to their natural history (ecological factors affecting their evolution) and differences in morphology (including differences in height, which will affect viewpoint and the visual information available to individuals in the same location). The implications of differences and applications for everyday handling and training of the dogs are discussed throughout.