How do nonhuman animals perceptually integrate figural fragments?

Visual information available from the environment is often fragmented in time and space. Integrating such fragmentary information is essential for animals to recognize meaningful objects surrounding them. It has been well-documented that humans perceptually organize visual inputs. In nonhumans, on the other hand, little has been known about their process of perceptual organization. This paper focuses amodal completion in nonhuman species as one of such processes. So far, several nonhuman species including primates, rodents, and birds have been tested for amodal completion of a variety of stimuli. Positive results have been obtained in most of the species tested. In particular, nonhuman primates have been suggested to share many characteristics of this process with humans-, a notable exception is pigeons. They have been shown to fail to complete with a variety of stimuli in a variety of procedures. However, this may be understood as a nature of this species adapted to their ecology. Surprising differences in perception in species that share many cognitive characteristics such as memory, concept formation, figure recognition, and so on, advises us to pay more attention to the correlation of perceptual systems and the way the species live in.