Opposed-set measurement procedure: A quantitative analysis of the role of local cues and intention in form perception

In 3 experiments with 48 undergraduates, the durations of alternative perceptual organizations of drawings and of a 3-dimensional object were used to provide quantitative measurement of local cue strength and of the viewer's intention. In Exp I, small line drawings of cubes were constructed so that a local depth cue (occlusion) at an upper intersection specified the cube's orientation while the lower intersection remained ambiguous. On any trial, Ss looked at either the biased or the unbiased intersection, with instructions to try to hold one organization or another; hence, the procedure was called the opposed-set method. The stimulus features nearest the S's instructed fixation and the viewer's perceptual task both had strong effects on reported durations. Exp II replicated the findings with a real object (a small 3-dimensional moving wire cube) as well as a drawn one. In Exp III, the opposed-set methodology was applied to figural completion. The quantitative data provided by this procedure show that the whole configuration is not the effective stimulus for perception; the data support a constructivist theory by posing problems for its strongest present competitors: the global minimum principle and the direct theory. (32 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).