Apparent motion and element connectedness.

Two experiments attempted to determine the effect of the topological property of connectedness on the perception of apparent motion. In Experiment I, direction detection points at subjective equality (PSEs) were measured in a motion competition paradigm. Results indicated that apparent motion was not more likely to be seen between topologically identical elements (e.g., two connected figures) than between elements similar in appearance, but which differed with respect to connectedness. This failed to replicate one finding of Chen (1985). Experiment II tested the possibility that connectedness might affect the quality or visibility of apparent motion. Displacement PSEs for the visibility of motion were measured. Apparent motion between identical figures was significantly more visible than apparent motion between figures similar in appearance, but of different connectedness. These results are discussed in terms of a two-stage model of the long-range motion system.