The effect of experience and of dots' density and duration on the detection of coherent motion in dogs.

Knowledge about the mechanisms underlying canine vision is far from being exhaustive, especially that concerning post-retinal elaboration. One aspect that has received little attention is motion perception, and in spite of the common belief that dogs are extremely apt at detecting moving stimuli, there is no scientific support for such an assumption. In fact, we recently showed that dogs have higher thresholds than humans for coherent motion detection (Kanizsar et al. in Sci Rep UK 7:11259, 2017). This term refers to the ability of the visual system to perceive several units moving in the same direction, as one coherently moving global unit. Coherent motion perception is commonly investigated using random dot displays, containing variable proportions of coherently moving dots. Here, we investigated the relative contribution of local and global integration mechanisms for coherent motion perception, and changes in detection thresholds as a result of repeated exposure to the experimental stimuli. Dogs who had been involved in the previous study were given a conditioned discrimination task, in which we systematically manipulated dot density and duration and, eventually, re-assessed our subjects' threshold after extensive exposure to the stimuli. Decreasing dot duration impacted on dogs' accuracy in detecting coherent motion only at very low duration values, revealing the efficacy of local integration mechanisms. Density impacted on dogs' accuracy in a linear fashion, indicating less efficient global integration. There was limited evidence of improvement in the re-assessment but, with an average threshold at re-assessment of 29%, dogs' ability to detect coherent motion remains much poorer than that of humans.