Abstract
Introduction: This study examines if slowness of the speed of sound can systematically influence multisensory precedence judgments, such as if a baseball base-runner visually reaches base before the auditory sound of the ball hitting the baseman's mitt. Because the speed of sound is only about 1100 feet per second, distant fans could judge the ball to arrive hundreds of msec later compared to a nearby umpire. Methods: 140 participants observed videos projected onto a gymnasium wall and made multisensory precedence judgments from 0, 100, or 200 feet. Participants judged which cue occurred first, visual ("safe") or auditory ("out") (no ties allowed). Experiment 1 used a visual flash versus auditory click, Experiment 2, colliding visual stimuli versus auditory click, and Experiment 3, films of base-runners with basemen catching balls. Results: Our findings verify that nearby observers exhibit a bias to favor sound occurring earlier, but at further distances tend to ignore the delay of sound reaching them. Thus, judgments were based largely on the order in which observers were exposed to the visual and auditory cues. This produced about a 100 msec change in threshold for each 100 feet more distant. The effect was mitigated in cases of colliding visual stimuli and actual baseball player videos when visual interception information was more apparent. Conclusions: We found observers exhibit a bias to favor auditory stimuli as occurring before visual stimuli (consistent with the slow speed of sound), but a tendency to not account for the delay of sound due to observation distance, with the offset-delay mitigated in more ecologically-valid conditions of visual interception. Our findings confirm that when distant visual information is impoverished, observers (such as fans making multisensory precedence judgments) typically do not fully account for acoustic delays due to the slow speed of sound, which could lead to arguments.
Meeting abstract presented at VSS 2016