1. VAS: Visual Analogue Scale, on which the subject marks his/her subjective craving on a 10-cm-long scale in response to the following question: "How much do you crave a joint/bong right now?" This "desire to smoke rating" has been shown to be sensitive to assess self-reported levels of craving in nicotine smoking (Schuh and Stitzer, 1995; King and Meyer, 2000).