Moving Targets: Effects of Transient Location in the Stream Bounce Display

Humans rely on perception to gain awareness and make sense of the environment. Though decades of research have investigated visual and auditory perception, there remain competing theories to explain how these sensory modalities interact. This study investigated the mechanisms underlying audiovisual perception using the stream/bounce display (SBD), wherein two digital objects move toward each other, completely superimpose, then move apart. This display has two valid percepts: either the objects appear to stream past or bounce off each other. When the motion sequence is presented in isolation, responses are biased toward streaming. However, when a transient (e.g. a tone) is presented at the point of coincidence (POC), the dominant percept flips toward bouncing. This study explored two competing hypotheses explaining this effect: the attentional hypothesis, which implicates the interruption of attention in the perception of bouncing; and the inference hypothesis, which instead suggests that ecological validity determines the dominant percept. Participants (n=28) watched a series of SBDs where a transient was presented at the moment of coincidence, either close to the motion sequence (maximising ecological validity with bouncing) or far from the sequence (maximising attentional diversion from the moving objects). The two hypotheses predict opposing patterns of results under this design. Results showed more ecologically valid presentations garnered higher bounce response rates when the transient was a visual flash alone or a flash paired with a tone (but not for a tone in isolation), providing partial support for the inference hypothesis. This finding highlights the importance of ecological validity in audiovisual perception and provides support for the inferential account of the stream/bounce display