One additional limitation for the current study findings is related to the nature of the study participants. In general, all participants were well educated, and in the case of the chronic marijuana smoking subjects, did not meet diagnostic criteria for marijuana dependence. This was somewhat surprising, given the smokers’ high levels and frequency of use. Marijuana smokers willingly and openly reported their level of use, (which was highly correlated with their urinary cannabinoid levels, adding credibility to their reporting), yet did not report any negative impact of their smoking on their social, physical, educational or occupational function, nor did they report experiencing symptoms associated with withdrawal while undergoing testing. In order to better understand the characteristics of the marijuana smoking sample, we examined scores for each of the seven elements which comprise marijuana dependence. We therefore calculated the percentage of the sample who endorsed (with a rating of 2 or subthreshold, or 3, threshold) the following criterion: tolerance (increased amount needed or decreased effect with same amount of marijuana= 33.3%; withdrawal = 0%; marijuana taken in larger amounts or for
