Fig. 2.

Adult female rats self-administer cannabis vapor at a greater rate than adult male rats. Mean (+/− SEM) number of active (A and B) and inactive (C and D) nosepoke responses made, vapor deliveries earned (E and F), and discrimination indices (G and H) for vapor containing 0 mg/ml (grey), 75 mg/ml (orange), 150 mg/ml (blue), or 300 mg/ml (green) cannabis extract. Rats were trained to respond on an FR-1 schedule of reinforcement for all 30 days of self-administration. Active and inactive responding panels include responses made during the 60 s timeout period, which had no programmed consequences. Male rats (left) are denoted with closed circles, while female rats (right) are denoted with open circles (n = 13/sex/group). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)