Point of subjective simultaneity
In multisensory integration research, Point of Subjective Simultaneity (PSS), typically measured in milliseconds, is defined as the stimulus onset asynchrony (SOA) at which a pair of signals from different sensory modalities is perceived as most simultaneous or synchronous. In other words, at PSS, an individual is most likely to integrate information from a pair of signals in the two given modalities. PSS Computation In behavioral experiments, test individuals are usually presented with pairs of signals from different sensory modalities (such as visual and audio) at different SOAs and asked to make either synchrony judgements (i.e. if the pair of signals appears to have come at the exact same time) or temporal order judgements (i.e. which signal appears to have come earlier than the other). Results from an individual's synchrony judgement tasks are typically fitted to a Gaussian curve with average perceived synchrony in percentage (between 0 and 1) on the y-axis and SOA (in milliseconds) on the x-axis, and the PSS of this individual is defined as the mean of the Gaussian distribution. Alternatively, results from an individual's temporal order judgement tasks are typically fitted to an S-shaped logistic psychometric curve, with percentage of trials where the subject responds that