Psychophysical estimation of the human depth combination rule

We describe a series of experiments designed to test (1) whether human observers combine depth cues using a weighted average when depth estimates in different maps are nearly consistent, (2) whether human observers behave as robust estimators when depths become increasingly inconsistent, and (3) whether the weights used in the linear rule of combination change to reflect the estimated reliability of different depth cues. We report initial experiments concerning texture and motion. The data are clearly consistent with the notion that the depth percent is a linear combination of the individual depth values portrayed by each cue. By randomly varying the shapes of the texture elements, the texture cue is artifically made unreliable, and the data support the hypothesis that unreliable cues are given less weight. Finally, there is an indication that when cues are strongly inconsistent, the weight on one of the cues is lowered, consistent with the hypothesis of robustness.