Transfer of Audio-Visual Temporal Training to Temporal and Spatial Audio-Visual Tasks

Temporal and spatial characteristics of sensory inputs are fundamental to multisensory integration because they provide probabilistic information as to whether or not multiple sensory inputs belong to the same event. The multisensory temporal binding window defines the time range within which two stimuli of different sensory modalities are merged into one percept and has been shown to depend on training. The aim of the present study was to evaluate the role of the training procedure for improving multisensory temporal discrimination and to test for a possible transfer of training to other multisensory tasks. Participants were trained over five sessions in a two-alternative forced-choice simultaneity judgment task. The task difficulty of each trial was either at each participant's threshold (adaptive group) or randomly chosen (control group). A possible transfer of improved multisensory temporal discrimination on multisensory binding was tested with a redundant signal paradigm in which the temporal alignment of auditory and visual stimuli was systematically varied. Moreover, the size of the spatial audio-visual ventriloquist effect was assessed. Adaptive training resulted in faster improvements compared to the control condition. Transfer effects were found for both tasks: The processing speed of auditory inputs and the size of the ventriloquist effect increased in the adaptive group following the training. We suggest that the relative precision of the temporal and spatial features of a cross-modal stimulus is weighted during multisensory integration. Thus, changes in the precision of temporal processing are expected to enhance the likelihood of multisensory integration for temporally aligned cross-modal stimuli.