What determines correspondence strength in apparent motion?

A sequence of static frames may produce the perception of coherent motion. The experiments described below investigated the psychophysical basis of this correspondence matching. Observers judged the direction of motion for "Gabor functions" which varied in spatial frequency, orientation or phase. The strongest determinant of correspondence was similarity of spatial frequency: objects tend to move toward neighbors of the same spatial frequency content. Orientation similarities also produced correspondence, although the effect was somewhat weaker than for spatial frequency. Phase played no role in determining correspondence.