There were two types of impulsivity measures used in the study: 1) Barratt impulsiveness scale, version 11 (BIS-11) (Barratt, 1985; Patton et al., 1995), a self-rated measure that assesses trait-related impulsivity, and 2) task-related behavioral (TRB) scores as derived from the performance of the gambling task. The BIS-11 consists of thirty items yielding a total score, and additional scores for three subcategories: motor impulsivity (acting without thinking), cognitive impulsivity (making decisions quickly), and non-planning (lack of prior planning or of future orientation). The TRB scores were of 3 categories: 1) reaction time (RT) for the task conditions and responses, 2) selection frequency (SF)—number of times a particular amount (10 or 50) was chosen—following a single trial of loss and following two consecutive trials of loss (based on the absolute score), and 3) SF followed by a losing or gaining trend (based on the cumulative score) in the previous 2 to 4 trials. The gaining and losing trends were computed based on the resultant outcome of the cumulative account of the preceding outcomes. For example, if the previous three outcomes were
