SPATIOTEMPORAL BOUNDARY FORMATION - THE ROLE OF LOCAL MOTION SIGNALS IN BOUNDARY PERCEPTION

Spatio-temporal boundary formation (SBF) refers to a perceptual proces s responsible for perception of moving, bounded surfaces from sequenti al changes in spatially separated local elements. Previous research ha s indicated that this process produces perception of global form, cont inuous boundaries and global motion from spatially and temporally spar se element changes. In the present paper, we sought to distinguish bet ween two classes of models for SBF: form-precedes-motion and motion-pr ecedes-form models. Experiment 1 tested the effects of the addition of spurious motion signals, a manipulation that should affect a motion-p recedes-form computation but not a form-precedes-motion computation. S hape identification in a 10-alternative forced-choice procedure was di srupted by this manipulation, supporting the former class of models, A particular computational scheme, edge orientation from motion (EOFM) instantiating a motion-precedes-form model is described and tested in Experiment 2. The EOFM model should be disrupted when initiating eleme nt changes occur in a certain type of sequential order, relative to ra ndomly arranged changes. Sequential changes markedly disrupted perform ance, supporting this EOFM approach. The results favor motion-precedes -form models of SBF and are consistent with the particular computation al scheme proposed. (C) 1997 Elsevier Science Ltd.