Abstract
Local-motion information can provide either 1-dimensional (1D) or 2-dimensional (2D) solutions. 1D signals occur when the aperture problem hasn't been solved, so each signal is an estimate of the local-orthogonal component of the object's motion. 2D signals occur when the aperture problem has been solved, so each signal is an estimate of the object's motion. Previous research (JoV, 2009, 9, 1-25) has shown that 1D and 2D signals are pooled differently, via intersection-of-constraints (IOC) and vector-average processes, respectively. Previous research (e.g. VisRes, 2003, 2290-2301) has also indicated that form cues can influence how motion signals are perceived. We investigated whether forms cues can affect the pooling of motion signals and whether they differentially affect the pooling of 1D and 2D signals. Global-Gabor (GG) and global-plaid (GP) stimuli were used. These stimuli consist of multiple apertures that contain either Gabors or plaids, respectively. In the GG stimulus the global solution is defined by having the Gabor carriers move (1D signals) such that they are consistent with a single IOC-defined solution. In the GP stimuli the plaid motion (2D signals) are consistent with a single VA solution. Form cues can be introduced by adding orientation information to the apertures that is either consistent (aligned with) or inconsistent (orthogonal to) with the global-solution. With the 1D stimuli, inconsistent form cues resulted in a loss of the IOC solution; observers instead perceived motion along the axis defined by the orientation cue. With the 2D signals, form cues had minimal effect. These results indicate that form cues can affect the pooling of 1D but not 2D signals. It is possible that the form cues do this by disambiguating the family of possible 2D solutions by providing the direction of motion, hence turning the 1D signals into 2D signals.
Australian Research Council through the ARC Centre of Excellence for Visual Science #CE0561903.