Contingent reinforcement of abstinence with individuals abusing cocaine and marijuana.
Paying for cocaine-free urine works, but you must also pay for marijuana-free urine if you want clients to quit both.
01Research in Context
What this study did
Adults who abused both cocaine and marijuana joined a day-treatment program.
They earned vouchers for drug-free urine plus counseling and job help.
The team first paid only for cocaine-free samples, then later added marijuana testing.
What they found
Cocaine use stopped quickly once vouchers required cocaine-free urine.
Marijuana use stayed high until the vouchers also required marijuana-free urine.
When marijuana testing ended, marijuana use crept back up.
How this fits with other research
Davidson et al. (2025) pooled 30 years of single-drug CM studies and found cocaine programs still beat the odds, so the 1991 strong effect holds today.
Andrade et al. (2014) swapped vouchers for paychecks and still saw clean cocaine urines, showing the rule works with real-world wages.
Heslop et al. (2007) got three adults off marijuana with talk-only ACT, no urine pay, hinting that some clients may quit weed without cash incentives.
Why it matters
If you run a CM program, test for every drug you care about.
Cocaine abstinence will likely follow the money, but marijuana needs its own contingency or it will stay.
Add both targets from day one to avoid a second round of shaping.
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02At a glance
03Original abstract
Two males diagnosed with cocaine dependence received a behavioral intervention comprised of contingency management and the community reinforcement approach. During the initial phase of treatment, reinforcement was delivered contingent on submitting cocaine-free urine specimens. The community reinforcement approach involved two behavior therapy sessions each week. Almost complete cocaine abstinence was achieved, but regular marijuana use continued. During a second phase, reinforcement magnitude was reduced, but remained contingent on submitting cocaine-free specimens. Behavior therapy was reduced to once per week. Cocaine abstinence and regular marijuana use continued. Next, reinforcement was delivered contingent on submitting cocaine- and marijuana-free specimens. This modified contingency resulted in an abrupt increase in marijuana abstinence and maintenance of cocaine abstinence. One- and 5-month follow-ups indicated that cocaine abstinence continued, but marijuana smoking resumed. These results indicate that the behavioral intervention was efficacious in achieving abstinence from cocaine and marijuana; maintenance, however, was achieved for cocaine only.
Journal of applied behavior analysis, 1991 · doi:10.1901/jaba.1991.24-657