We investigated how subjects perceive the temporal relationship of a light-flash and a complex acoustic signal. The stimulus mimics ubiquitous events in busy scenes which are manifested as a change in the pattern of ongoing fluctuation. Detecting pattern emergence inherently requires integration over time; resulting in such events being detected later than when they occurred. How does delayed detection-time affect the perception of such events relative to other events in the scene?
To model these situations, we use sequences of tone-pips with a time-frequency pattern that changes from random to regular (‘REG-RAND’) or vice versa (‘RAND-REG’). REG-RAND transitions are detected rapidly, but RAND-REG take longer to detect (~880ms post nominal-transition). Using a Temporal Order Judgment task, we instructed subjects to indicate whether the flash appeared before or after the acoustic transition. The point of subjective simultaneity between the flash and RAND-REG does not occur at the point of detection (~880ms post nominal-transition) but ~470ms closer to the nominal acoustic-transition. This indicates that the brain possesses mechanisms that survey the proximal history of an ongoing stimulus and automatically adjust perception to compensate for prolonged detection time, thus producing more accurate representations of cross-modal scene dynamics. However, this re-adjustment is not complete.