Figure 2.

Schematic representations of the five key events comprising conditions in Experiment One. (A) Key events in the six conditions that are meant to generate perceptually ambiguous motion, that is, motion in which the two equal contrasts disks could be seen either as streaming through one another or bouncing off one another. Ambiguous: key events in the basic, control condition; Ambiguous + Sound: a click sound is presented as the two disks coincide; Ambiguous + Sound + Medium occluder: in addition to the click sound, the disks’ coincidence is obscured by opaque occluder presented for 0.233 s. In the next three conditions, no sound is presented. Ambiguous + Short occluder: the disks’ coincidence is obscured by opaque occluder presented for 0.117 s; Ambiguous + Medium occluder the disks’ coincidence is obscured by opaque occluder presented for 0.233 s; Ambiguous + Long occluder: the location at which the disks would coincide is obscured by opaque occluder presented for 1.5 s, that is, the entire duration of the moving stimulus. (B) Key events in the six conditions that promoted unambiguous motion. Two disks of unequal luminances moved toward each other, coincided, and then either returned to their respective starting locations (promoting a percept of bouncing; shown in sequence 1) or continued to the opposite side of the display (promoting a percept of streaming; shown in sequence 2). In sequences 3 and 4, at the moment of the disks’ coincidence, a click sound was inserted into a stimulus that promoted bouncing (sequence 3) or one that promoted streaming (sequence 4). In the final two sequences, a 0.233-s occluder was inserted into a sequence that promoted bouncing (sequence 5) or one that promoted streaming (sequence 6).