The current study examined cardiac and behavioral responsesto changing auditory and visual information while usingmodified oddball tasks. When instructed to press the samebutton for auditory and visual oddballs, auditory dominancewas found with cross-modal presentation slowing downvisual response times and decreasing visual accuracy. Wheninstructed to make separate responses to auditory and visualoddballs, visual dominance was found with cross-modalpresentation slowing down response times and decreasingauditory accuracy. However, examination of cardiacresponses that were time-locked to stimulus onset show cross-modal facilitation effects, with discrimination of oddballs andstandards occurring earlier in the course of processing in thecross-modal condition than in the unimodal conditions. Thesefindings shed light on potential mechanisms underlyingmodality dominance effects and have implications on tasksthat require simultaneous processing of auditory and visualinformation.