The world from a cat?s perspective ? statistics of natural videos

Abstract

The mammalian visual system is one of the most intensively investigated sensory systems. However, our knowledge of the typical input it is operating on is surprisingly limited. To address this issue, we seek to learn about the natural visual environment and the world as seen by a cat. With a CCD camera attached to their head, cats explore several outdoor environments and videos of natural stimuli are recorded from the animals' perspective. The statistical analysis of these videos reveals several remarkable properties. First, we find an anisotropy of oriented contours with an enhanced occurrence of horizontal orientations, earlier described in the "oblique effect" as a predominance of the two cardinal orientations. Second, contrast is not elevated in the center of the images, suggesting different mechanisms of fixation point selection as compared to humans. Third, analyzing a sequence of images we find that the precise position of contours varies faster than their orientation. Finally, collinear contours prevail over parallel shifted contours, matching recent physiological and anatomical results. These findings demonstrate the rich structure of natural visual stimuli and its direct relation to extensively studied anatomical and physiological issues.

Selective interhemispheric circuits account for a cardinal bias in spontaneous activity within early visual areas

“…Indeed, statistical properties of natural scenes as viewed by cats exhibit a bias for cardinal with prevalence for horizontal contours (Betsch et al, 2004). A bias for cardinal orientations is also found in human natural scenes (Nasr and Tootell, 2012).…”

Responses of blowfly motion-sensitive neurons to reconstructed optic flow along outdoor flight paths

“…Natural environments are characterized by large variation in contrast, a patchy distribution of objects and a pronounced depth structure. Nervous systems have evolved to compute behaviourally relevant information under such complex natural conditions in an efficient and robust way and their design is likely to reflect the statistical and dynamical properties of these conditions (Betsch et al 2004;Burton and Laughlin 2003;Eckert and Zeil 2001;Kayser et al 2004;Olshausen and Field 1996;Reinagel 2001;Simoncelli 2003;Simoncelli and Olshausen 2001;van Hateren 1997). Since the structure of the environment and the animal's own movements both determine the image motion pattern animals experience, the processing of natural optic flow can only be investigated from the viewpoint of the behaving animal (e.g.…”

The contribution of active body movement to visual development in evolutionary robots

“…Betsch et al (2004) showed that the exploration strategy and the difference of vantage point of animals significantly altered the statistics of natural scenes. This is fully consistent with the lesson from the studies of visuo-tactile interfaces for blind people (see Bach-y-Rita and Kercel, 2003, for a review).…”