The effects of age upon the perception of depth and 3-D shape from differential motion and binocular disparity

The ability of younger and older adults to perceive the 3-D shape, depth, a nd curvature of smooth surfaces defined by differential motion and binocula r disparity was evaluated in six experiments. The number of points defining the surfaces and their spatial and temporal correspondences were manipulat ed. For stereoscopic sinusoidal surfaces, the spatial frequency of the corr ugations was also varied. For surfaces defined by motion, the lifetimes of the individual points in the patterns were varied, and comparisons were mad e between the perception of surfaces defined by points and that of more eco logically valid textured surfaces. In all experiments, the older observers were less sensitive to the depths and curvatures of the surfaces, although the deficits were much larger for motion-defined surfaces. The results demo nstrate that older adults can extract depth and shape from optical patterns containing only differential motion or binocular disparity, but these abil ities are often manifested at reduced levels of performance.