Long-Range Apparent Motion as a Result of Perceptual Organisation

Abstract

Five kinds of percept have been found to occur when two different stimulus objects are simultaneously presented, exchanging positions with each other in successive exposures. These five percepts can be classified as follows: (i) Appearance-Disappearance (succession), (ii) Lateral Motion, (iii) Depth Motion, (iv) Transmutation (in colour, brightness, and/or shape), and (v) Overlapping (simultaneity). Results of three experiments indicate that relative dominance among these five percepts systematically depends upon differences between the two stimulus objects in colour, luminance, shape, and size. The relative dominance depended upon the stimulus onset asynchrony (SOA) between successive presentations and on the spatial separation between the two objects. Lateral Motion became more dominant as a result of (a) an increase in the number of stimulus attributes differing between the two objects, (b) an increase in the SOA, or (c) a decrease in the distance between the two objects. Colour difference, even without a luminance difference, was one of the determinants for Lateral Motion. Depth Motion frequently occurred when the two objects differed in size and the SOA and the distances between them were relatively great. Transmutation occurred when the objects differed in colour, luminance, or shape. Perceptual modes (ii) to (iv) can be understood as different results of perceptual organisation that always maintains perceptual identity of objects and maintains perceptual constancy of their attributes as much as possible. Long-range apparent motion could be a result of such perceptual organisation.

Effects of Similarity on Apparent Motion and Perceptual Grouping

“…This means that effects of similarities or differences work additively across different perceptual attributes on both phenomena, as it has been shown partly by Caelli et al (1993) for apparent motion. The results of these experiments confirm the tendency found for crossed phi by Oyama et al (1994), in the present experiments more quantitatively for single phi. As the difference in either colour, luminance, size, and shape in part 1, or their combinations in part 2, increased between heterogeneous stimulus elements, apparent motion, as well as perceptual grouping, tended to occur less easily between them.…”

“…However, we consider these findings from a broader point of view, in which spatial position is also regarded as one of the perceptual attributes in the same way as colour, brightness, size, and shape, as suggested by Foster (1978), Oyama (1997), Oyama et al (1994), and Shechter and Hochstein (1989). We consider that all similarities or differences in these perceptual attributes work together, as shown in the results of part 2 of the present study.…”

“…(2) See footnote 1. size (area) difference, and that between triangle and square in matched separation, in both apparent motion and perceptual grouping. The present study indicates that luminance is as effective as size, as shown in Oyama et al (1994), whereas luminance was found to be less effective than size by Shechter and Hochstein (1989). More exact measurements of matched separations will make it possible to compare quantitatively relative contributions of similarities in various perceptual attributes on the two perceptual phenomena, on one hand, and to scale perceptual similarities multidimensionally in dynamic situations, on the other hand.…”

“…This puts apparent motion in line with various perceptual constancies, as discussed by Oyama (1997). He pointed out, on the basis of experimental work by Oyama et al (1994), that apparent motion is only one of possible solutions of perceptual organisation that keep perceptual changes down to a minimum and maintain perceptual constancy as much as possible, and that apparent motion occurs when it can reduce the total perceptual changes more and make our perceptual world more stable than other possible percepts, such as sudden appearance and disappearance of objects in different positions. He and Nakayama (1994) and Shimojo and Nakayama (1990) indicated that the effects of perceptual attributes on apparent motion are not determined at the early filtering level, but at a higher perceptual processing level, including that for amodally perceived surface shapes.…”

Spatiotemporal Balance in Competing Apparent Motion is Not Predicted from the Strength of the Single-Motion Percept

“…The perceived apparent motion seems here to be a product of the visual system that should always strive for minimum change (Koffka 1935): in competing apparent motion, the system should prefer smaller spatiotemporal changes so that a motion candidate with the smaller value of AISI B log L is perceived. Such understanding matches well with the widely accepted view that apparent motion is an example of perceptual constancy, or a tendency to avoid changes to the greatest possible extent (Oyama 1997;Oyama et al 1994Oyama et al , 1999.…”