Measures of Heart Rate and Skin Conductance to Orienting Stimuli during Repetitive Administration of Marijuana*

Summary To study cumulative effects of marijuana on basal measures of heart rate and skin conductance (SC) and phasic SC, 24 human males were randomly assigned to three groups of ft subjects each. Subjects lived on an experimental ward for 36 days. For the first 4 and the lost 4 days, no marijuana was administered. During the intervening 28 days, subjects smoked one marijuana cigarette daily which weighed approximately 0.5 grams. Dosage of tetrahydrocannabinol (THC), depending on group membership, was either placebo, 1% THC or 2% THC. Each subject was seen for psychophysiological testing during one initial baseline day, four intoxication days, and two post‐intoxication days. Testing was done at a time when acute marijuana effects were minimal, and consisted of presenting a 67 Db tone orienting sequence under both nonsignal and signal conditions. Basically, the results indicated no detectable differences among the groups, due to the chronic administration of marijuana, on either of the physiological systems measured. The results were related to the effects of acute marijuana intoxication and Sokolov's theory of the orienting response.