Dissociations between stereoacuity and visual acuity with binocular night vision goggles.

Night vision goggles (NVGs) enhance vision under scotopic conditions by amplifying near-infrared light and converting it to a wavelength that can be seen by the human visual system. Although significantly more expensive than monocular systems, binocular NVGs provide the user with independent inputs to each eye, and therefore facilitate stereopsis, the ability to discriminate differences in depth from binocular cues. Past work examining stereopsis through NVGs has been mixed, with early-generation systems showing no evidence for stereopsis while more-modern systems show some evidence for (and others against) stereopsis, albeit at levels below that observed under natural photopic viewing conditions. These studies have examined stereopsis through NVGs under ideal conditions that isolate binocular contributions to depth perception. In the present study, stereopsis through NVGs was examined under more realistic conditions and for more operationally relevant tasks. The results show that stereopsis through NVGs persists even under degraded viewing conditions and provides a binocular advantage for real-world tasks where the perception of depth plays an important role. These results show that limitations in stereoacuity through NVGs are not driven by visual acuity limits, as has been previously argued, and more generally a dissociation between visual acuity and stereoacuity.