An important consideration in interpreting potential effects of alcohol use is to verify that participants did not vary at baseline in major behavioral domains related to affective dispositions or externalizing tendencies, which might confound interpretation. The Achenbach Youth Self-Report Inventory (YSR; (41)) was utilized to measure externalizing tendencies. To measure major personality trait domains, the Multidimensional Personality Questionnaire (MPQ) was administered in brief form (42) to assess tendencies toward positive emotion, negative emotion and behavioral constraint. Constraint and its facets are of particular interest, because they reflect high impulse control, low risk-taking, and adherence to conventional rules. Constraint is operationalized in relation to sub-domains of Control, Harm Avoidance, and Traditionalism. Control reflects tendencies to be reflective; cautious, planful and level-headed. It is the opposite of impulsivity. Harm Avoidance reflects a tendency to avoid participation in dangerous or thrill-seeking activities (e.g. skydiving; natural disasters). High scorers prefer safer, even tedious, activities. Traditionalism reflects a bias toward the endorsement of high moral standards, religious values and institutions, positive regard for parents, the endorsement of strict child-rearing practices, and valuation of conventional propriety
