The Relation Between Impulsivity and Estimation of Marijuana Weight

Until recently, marijuana research has often relied on self-reported frequency of use (e.g., days used per month). These estimations may oversimplify use at times, as they can only infer the quantity that one uses, rather than directly measure it. While some studies have estimated quantity (e.g., number of joints, grams), research has supported that user estimates of marijuana weight are often inaccurate and overestimate the true quantity. Since weight misestimation varies by participant, it may be important to identify individual difference factors (e.g., personality) that influence weight estimation. One such factor may be impulsivity, as it is known to relate to other marijuana-use measures (e.g., frequency, consequences). However, research has yet to examine the specific relation between impulsivity and misestimation of marijuana weights. The present study investigated impulsivity as a predictor of marijuana quantity estimation, using objectively weighed quantity data. We hypothesized that impulsivity facets would relate to marijuana quantity misestimation. We asked attendees at a marijuana- related event to roll a joint or pack a bowl, and then take, among a battery of measures, the SUPPS-P Impulsive Behavior Scale. We found that negative urgency, positive urgency, and lack of perseverance were not significantly associated with misestimation, while lack of premeditation was significantly negatively related to misestimation. Findings indicated that individuals who lacked in premeditation made more accurate quantity estimates than those higher in premeditation. Future directions should investigate the relation between impulsivity, marijuana intoxication, and marijuana quantity estimation.