Is autostereoscopy useful for handheld AR?

Some recent mobile devices have autostereoscopic displays that enable users to perceive stereoscopic 3D without lenses or filters. This might be used to improve depth discrimination of objects overlaid to a camera viewfinder in augmented reality (AR). However, it is not known if autostereoscopy is useful in the viewing conditions typical to mobile AR. This paper investigates the use of autostereoscopic displays in an psychophysical experiment with twelve participants using a state-of-the-art commercial device. The main finding is that stereoscopy has a negligible if any effect on a small screen, even in favorable viewing conditions. Instead, the traditional depth cues, in particular object size, drive depth discrimination.