Ambiguity in perception and experimentation

Bruno and Cutting (1988) varied four monocular cues to perceived depth in a factorial design. Subjects judged the distance between test objects. Given main effects in the analysis of variance, the authors concluded that the perceivers integrated the four different sources of information, as opposed to simply selecting a single source. Given no interactions in the analysis of variance, the authors concluded that the integration process was additive rather than multiplicative. The ambiguity inherent in Bruno and Cutting's experiments and analyses is discussed. As presented, their results did not provide evidence for integration of depth cues or evidence for additivity, independence, and parallel processing of the cues. An additional analysis of the distribution of the rating judgments given by their subjects, however, provides some evidence for integration of the cues. The fuzzy logical model of perception (FLMP) is extended to describe perceptual recognition of depth. The model assumes independence of the cues during feature evaluation and a nonadditive integration process in which the least ambiguous cues have the greatest impact on the judgment. The FLMP is contrasted with a model assuming additivity of the cues. Because both models describe the results equally well, it remains for future researchers to provide definitive tests between the models.