What makes the Mueller a liar: A multiple-cue approach

Subjects made magnitude estimations of fins-in and fins-out Mueller Lyer stimuli. Shaft length, fin length, and fin angle were within-subjects variables, and the sitmuli could be either conventional solid drawings or dot forms, a between-subjects variable. The parametric effects of these variables were similar to results previously obtained. However, principal emphasis was given to lens model and related multivariate analyses of the subjects' judgments. These analyses suggested that no single "critical" cue seemed to account for the illusion. Rather, various sets of cues could be formulated to simulate the subjects' judgmental behavior equivalently. In addition, field-independent subjects showed better knowledge of the cue structure than field-dependent subjects. In the main, subjects in this experiment performed like subjects have in tasks not involving visual illusions with multiple sources of information varying in their relevance.