Baseline impulsivity used total scores from adolescent (< age 18) and adult (≥ age 18) Barratt Impulsivity Scale forms (Stanford et al., 2009). This instrument scores 30-items from 1 (rarely or never) to 4 (usually) regarding statements like “I plan carefully,” “I do things without thinking,” “I am self-controlled,” and “I act on impulse.” The Barratt was selected because the questions were relevant to COGA’s electrophysiological measures, and most other scales are more time consuming and/or have a focus on hostility or aggression that were not central to the goals of these analyses (Hollander et al., 2000). The Barratt has Cronbach alpha=.83 and 1 month retest reliabilities of .83 (Stanford et al., 2009), with values for the adolescent and adult versions combined by using z-scores for each of the two forms.
