Sequential stereopsis using high-pass spatial frequency filtered textures

Enright [(1995). Perception, 24 (suppl.), 32-33; (1996). Vision Research, 36, 307-312] described a simple piece of equipment for demonstrating a perceptual mechanism he called sequential stereopsis. The equipment requires an observer to set two textured targets seen behind a pair of small viewing ports to appear equi-distant. The principle upon which the apparatus depends is the use of textures whose elements cannot be resolved in peripheral vision at the eccentricity determined by the target separation. Enright used a fine sandpaper for this purpose. We have conducted two similar experiments using high bandpass filtered textures which eliminate any possibility that the low spatial frequency content of sandpaper textures could play a role. Our results corroborate Enright's general conclusions on sequential stereopsis, while at the same time showing that high-pass textures do not give wholly similar results to sandpaper.