Auditory temporal modulation of the visual Ternus effect: the influence of time interval.

Research on multisensory interactions has shown that the perceived timing of a visual event can be captured by a temporally proximal sound. This effect has been termed 'temporal ventriloquism effect.' Using the Ternus display, we systematically investigated how auditory configurations modulate the visual apparent-motion percepts. The Ternus display involves a multielement stimulus that can induce either of two different percepts of apparent motion: 'element motion' or 'group motion'. We found that two sounds presented in temporal proximity to, or synchronously with, the two visual frames, respectively, can shift the transitional threshold for visual apparent motion (Experiments 1 and 3). However, such effects were not evident with single-sound configurations (Experiment 2). A further experiment (Experiment 4) provided evidence that time interval information is an important factor for crossmodal interaction of audiovisual Ternus effect. The auditory interval was perceived as longer than the same physical visual interval in the sub-second range. Furthermore, the perceived audiovisual interval could be predicted by optimal integration of the visual and auditory intervals.