Scoring criteria for response latency and habituation in electrodermal research: a critique.

Recent evidence, particularly in research on the skin conductance orienting response (SCOR) in schizophrenia, suggests that differences in scoring criteria may be important sources of error and variability in studies of electrodermal responses to discrete stimuli and their habituation. Although a wide variety of response latency criteria have been used in published studies, empirical evidence suggests that responses occur in a narrow and early post-stimulus time window. Data are presented demonstrating that the intra-subject variability of response latency is low when responses are scored within a narrow time window, but that broader time windows include more variable-latency responses that may represent spontaneous activity. The commonly-used criterion of three no-response trials as an habituation endpoint may also introduce contamination by spontaneous activity; available evidence favors a two-trials criterion. Analyses such as the ones presented here permit testing of the specificity of scoring criteria for responses elicited by experimental stimuli.