Stimulus onset asynchrony

Stimulus-onset asynchrony (SOA) is a measure used in experimental psychology. SOA denotes the amount of time between the start of one stimulus and the start of another stimulus. In psycholinguistics the stimuli are typically a prime and a target, in which case the stimulus-onset asynchrony is measured from the beginning of the prime until the beginning of the target. This time can be manipulated experimentally to determine its effects on other dependent measures such as reaction time or brain activity.

For an example of the application of stimulus-onset asynchrony, see Psychological Refractory Period.