Visual Depth Perception via Motion Parallax by Chickens (Gallus Gallus) in an Operant Chamber

Abstract

There are multiple cues animals use to infer depth from the two-dimensional information that passes across the retina. Differential motion of objects across the retina, or motion parallax, has been extensively studied in humans and primates, but little information is available on avian species. This set of experiments utilised an operant chamber and computer-generated stimuli to investigate the parallax discrimination abilities of domestic chickens (Gallus gallus). The birds were able to discriminate between a single stationary and a single moving object, but performance dropped to chance, and biased responding developed when parallax stimuli were introduced. A second operant chamber that forced the animals to view stimuli from a distance also resulted in chance performance. Birds may require motion across both eyes to discriminate depth when displayed on a screen.