The delay between stimulus presentation and some aspect of the response. Onset latency relates to the delay between the stimulus presentation and the beginning of the response, while the peak latency uses the time of the maximum amplitude of the response as the second point. Latencies of specific physiologic responses vary. The latency of an electrodermal response, for example, from stimulus onset is about one to three seconds for the average person, while hormonal influences on blood pressure require several seconds more. A significant departure from typical latencies can indicate that a given response is unrelated to the stimulus, that there are problems in attention for the subject, or that countermeasures are being engaged. Because of individual differences, within-subject analyses are to be preferred.
