GLOBAL MOTION DETECTION IN DOGS (CANIS FAMILIARIS)

Motion perception is one of the main properties of the visual system. Although characteristics of this ability are well studied in humans, there is no data about dogs’ sensitivity in detecting global motion. The aim of our study was to define thresholds of global motion perception in dogs and to investigate how features of the stimulus affect such threshold. The procedure was based on discrimination tasks where subjects had to discriminate between two stimuli presented on touch screens, representing kinetograms with different percentages of coherently moving dots. Three pet dogs participated in three experiments. Before each experiment subjects were trained to discriminate a positive stimulus (80% of coherently moving dots) from a negative one (0% of coherently moving dots). Afterwards, dogs underwent three tests (each containing 200 trials) varying the percentage of coherence (Exp 1), the density (Exp 2) and the lifetime of the dots (Exp 3). Results of Exp 1 show that the threshold of global motion perception varies between 36.1% and 39.0%. Decreasing dot density (Exp 2) had a great negative impact on the performance of the subjects, while decreasing dot lifetime (Exp 3) did not affect it. Dogs’ perception threshold of global motion is similar or higher than in other species (e.g. cats, seals and humans) that have been tested in similar experimental conditions. This questions the general claim on dogs’ higher performance in perceiving motion.