PUB - Publikationen an der Universität Bielefeld

Studies on multisensory perception often focus on simplistic conditions where one signal is presented per modality. Yet, in everyday life we encounter multiple signals per modality that may be associated with each other. Using the spatial ventriloquism paradigm as model, we tested how the presence of two visual stimuli shapes sound location judgements. Across three experiments we systematically paired one sound with either one or two visual stimuli that differed in relative timing and spatial offset to the sound. We focused on two biases typically studied in this paradigm, the ventriloquism effect and the trial-wise aftereffect. Our results show that these are not shaped by a single visual stimulus in a winner-takes-all manner but rather by their collective influence. In particular, the contribution of individual visual stimuli to the ventriloquism bias depends on their own relative timing to the sound and the temporal context provided by the other visual signal. Depending on this context, two visual signals influence the collective bias with comparable or asymmetric weights, which we attribute to the temporal evolvement of evidence for sensory causal relations during the individual trials. Concerning the aftereffect, we show that this emerges following both auditory and visual judgements in the preceding AV trials and following asynchronous AV stimulus pairs, confirming the notion that this reflects an automatic adjustment to spatial discrepancies.