Judged: two independent readers; copy check clear.
stereoscope
stereoscope A stereoscope is a device used to present two companion images separately to the two eyes so they can be fused into a single binocular percept.
A stereoscope is a device used to present two companion images separately to the two eyes so they can be fused into a single binocular percept. In this context, a hand-held mirror stereoscope enables cross-fusion, which can make local visual differences stand out during search tasks.