Shaping cocaine abstinence by successive approximation

Cocaine-using methadone-maintenance patients were randomized to standard co ntingency management (abstinence group, n = 49) or to a contingency designe d to increase contact with reinforcers (shaping group, n = 46). For 8 weeks , both groups earned escalating-value vouchers based on thrice-weekly urina lyses: The abstinence group earned vouchers for cocaine-negative urines onl y; the shaping group earned vouchers for each urine specimen with a 25% or more decrease in cocaine metabolite (first 3 weeks) and then for negative u rines only (last 5 weeks). Cocaine use was lower in the shaping group, but only in the last 5 weeks, when the response requirement was identical. Thus , the shaping contingency appeared to better prepare patients for abstinenc e. A 2nd phase of the study showed that abstinence induced by escalating-va lue vouchers can be maintained by a nonescalating schedule, suggesting that contingency management, can be practical as a maintenance treatment.