What factors determine the stabilization of a bi-stable stimulus?

It was recently reported that the perceptual alternation in viewing bi-stable stimuli could be slowed down, and even brought to a standstill, if the stimuli are presented intermittently. What are the factors that are important for the preservation of one percept over sequential presentations? Investigating the factors that affect this stabilizing effect will help us to understand the mechanism of the perceptual alternation for these bi-stable images. We adopted a bi-stable rotating cylinder as the stimulus. It is a parallel projection of 200 random dots painted on the surface of a rotating cylinder. On computer screen, these 200 dots move left and right with their speed following a sinusoidal function. In our experiment, the stimulus was presented with a 1-second on-time and 2-second off-time paradigm. The key manipulation is that in alternating presentations, we physically changed certain properties of the stimulus, including the spatial location, the color of the dots, the size of the cylinder, or the moving speed of the dots. In all six observers tested, changing the color, the moving speed of the dots, or the size of the cylinder had no or minimal effect on the stabilization of perceived rotating direction. The only factor that affected the stabilizing effect was the location change. Changing the location of the stimulus often resulted in a change in perceived direction. Interestingly, it seemed that the perception of the rotating direction was stabilized in a given location but independent between locations. Furthermore, switching between two locations projecting to the two hemispheres was more likely to break the stabilizing effect than switching between locations that project to the same hemisphere. These results suggest that the stabilizing effect is affected by retinotopically specific mechanisms, but is insensitive to the features that define the object.