Perceptual economy and the impression of visual depth

Three experiments were carried out to investigate the hypothesis that the impression of visual depth given by gradient patterns is due to the operation of a principle of “perceptual economy.” The first experiment showed that the greater the number of values of the gradient variables in a pattern, the stronger was the tridimensional impression given by that pattern. The second showed that the greater the number of gradient variables, the less the amount of the pattern that had to be exposed before a tridimensional response was elicited. The third showed that judged slants increased as a function of the number of gradient variables in each pattern. The results suggest that the impression of visual depth given by a pattern represents a compromise between the economy gained from making a tridimensional specification of the elements in the pattern and the possible cost of making an error in coding the information in this way.