The present paper provides a primer on percentile reinforcement schedules, which have been used for two decades to study response differentiation and shaping in the laboratory. Arranged in applied settings, percentile procedures could be used to specify response criteria, standardizing treatment across subjects, trainers, and times to provide a more consistent training environment while maintaining the sensitivity to the individual's repertoire that is the hallmark of shaping. Percentile schedules are also valuable tools in analyzing the variables of which responding is a function, both inside and outside the laboratory. Finally, by formalizing the rules of shaping, percentile schedules provide a useful heuristic of the processes involved in shaping behavior, even for those situations that may not easily permit their implementation. As such, they may help further sensitize trainers and researchers alike to variables of critical importance in behavior change.

Lever pressing by two squirrel monkeys was maintained under a variable-interval 60-second schedule of food presentation. When response-dependent electric shock was made contingent on comparatively long interresponse times, response rate increased, and further increases were obtained when the minimum interresponse-time requirement was decreased. When an equal proportion of responses produced shock without regard to interresponse time, rates decreased. Thus, shock contingent on long interresponse times selectively decreased the relative frequency of those interresponse times, and increased the relative frequency of shorter interresponse times, whereas shock delivered independent of interresponse times decreased the relative frequency of shorter interresponse times while increasing the frequency of longer ones. The results provide preliminary evidence that interresponse times may be differentiated by punishment, further supporting the notion that interresponse times may be considered functional units of behavior.

Objective Contingency management (CM) can effectively treat addictions by providing abstinence incentives. However, CM fails for many who do not readily meet the abstinence criterion and earn incentives. Shaping may improve outcomes in these hard-to-treat (HTT) individuals, as shaping sets intermediate criteria for incentive delivery between the present behavior and total abstinence. This should result in HTT having improving rather than poor outcomes throughout treatment. We examined if shaping improved outcomes in HTT smokers (those never abstinent during a 10-visit baseline). Method Smokers were stratified into HTT (n=96) and easier-to-treat (n=50; ETT – those abstinent at least once during baseline), and randomly assigned to either standard CM or shaping (CMS). CM provided incentives for breath carbon monoxide (CO) levels < 4 ppm (approximately 1-day of abstinence). CMS shaped abstinence by providing incentives for CO levels lower than the 7th lowest of the participant’s last 9 samples or < 4 ppm. Interventions lasted for 60 successive weekdays visits. Results Cluster analysis identified four groups of participants: stable successes; improving; deteriorating; and poor outcomes. In comparison to ETT, HTT were more likely to belong to one of the two unsuccessful clusters (odds ratio (OR)=8.1, 95% CI [3.1, 21]). This difference between the HTT and the ETT was greater with CM (OR=42 [5.9, 307]) than with CMS where the difference between HTT and ETT was not significant. Assignment to CMS predicted membership in the improving (P=0.002) as compared to the poor outcomes cluster. Conclusion Shaping can increase the effectiveness of CM for HTT smokers.

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