“…Rewards may take multiple forms, but the most common include vouchers that may be exchanged for goods or services, prizes, or the granting of some form of privilege. Contingency management approaches have been shown to improve retention and to increase abstinence with various substance-abusing populations, including those dependent on cocaine (Higgins et al, 1994), marijuana (Budney, Higgins, Radonovich, & Novy, 2000), alcohol (Petry, Martin, Cooney, & Kranzler, 2000), and opioids (Bickel, Amass, Higgins, Badger, & Esch, 1997;Silverman, Chutuape, Bigelow, & Stitzer, 1996).…”