​Psychological Terms — Expanded Paraphrase
An anaglyptoscope is an instrument designed to change how light falls on a three-dimensional object. By reversing illumination patterns, the device alters the usual balance of light and shadow. This helps researchers study visual perception, especially how the brain interprets shape and depth through shading.
Because shading often helps us resolve a 3-D shape from a 2-D image, this tool provides insight into perceptual processes such as chiaroscuro—the contrast of light and dark that conveys form.