Assigned 48 volunteer adult males to four groups: a marijuana high dose, a marijuana low dose, a placebo, and a coltsfoot group. Each S participated in two 80-minute sessions; one involved listening to music, socializing, and smoking the drug, and the second was identical to the first with the addition of two extra placebo cigarettes which contained finely cut amounts of human hair. The odor of burning hair was rated previously as quite aversive by non-intoxicated Ss. Contrary to expectation, Ss in the odor condition indicated on self-ratings that they became significantly more intoxicated after the smoking of the hair cigarette. The opposite effect was found with a pulse rate measure. An additional 24 Ss were divided into high and low dose marijuana groups and run in an odor session, in which they were informed prior to smoking of the hair content. Heart rate for these Ss decreased significantly more than for the comparable uninformed Ss, although self-ratings continued to reflect increased intoxication.