The spatial constraint in intersensory pairing: no role in temporal ventriloquism

A sound presented in temporal proximity to a light can alter the perceived temporal occurrence of that light (temporal ventriloquism). The authors explored whether spatial discordance between the sound and light affects this phenomenon. Participants made temporal order judgments about which of 2 lights appeared first, while they heard sounds before the 1st and after the 2nd light. Sensitivity was higher (i.e., a lower just noticeable difference) when the sound-light interval was approximately 100 ms rather than approximately 0 ms. This temporal ventriloquist effect was unaffected by whether sounds came from the same or a different position as the lights, whether the sounds were static or moved, or whether they came from the same or opposite sides of fixation. Yet, discordant sounds interfered with speeded visual discrimination. These results challenge the view that intersensory interactions in general require spatial correspondence between the stimuli.