The effects of subthreshold synchrony on the perception of simultaneity

We aimed to examine the effects of subthreshold synchrony and asynchrony on the perception of simultaneity. We rendered simultaneous or asynchronous luminance changes below detection thresholds by embedding them in a sequence of rapidly onsetting flankers. Still, simultaneity of subthreshold luminance changes can influence decisions concerning the simultaneity of clearly visible changes in luminance: across a range of very brief target SOAs, subthreshold synchrony was found to increase the tendency to report ‘simultaneity’, although simultaneity thresholds themselves remained largely uninfluenced. These effects are discussed in terms of the early synchronization of sensory mechanisms and the extent to which this pattern of synchronization influences the perception of relations between events in time.