Methods and mechanisms in electrodermal studies of omission responding.

Barry and O'Gorman (1987) employed a response-averaging technique to investigate the electrodermal orienting response (OR) to stimulus omission. We obtained reliable evidence of increased response latency to stimulus omission, supporting an explanation of the missing-stimulus effect in terms of Maltzman's voluntary OR. Wilson's (1989) commentary on our article addresses both methodological and theoretical aspects. This response first examines his methodological difficulties, and provides simulation exercises which serve as a validation of our procedure. We then examine Wilson's theoretical points. His alternative theoretical explanation of the missing-stimulus effect, in terms of a systematic bias in the time-keeper of the stimulus-comparator process, is shown to be untenable. His remaining problem, concerning what he terms "assessment of stimulus significance", appears to have arisen through misinterpretation of our theory. A clarification of our theoretical position indicates the internal consistency of our use of "significance" and "voluntary OR".