Exploring the limits and utility of operant conditioning in the treatment of drug addiction

This article describes a research program to develop an operant treatment for cocaine addiction in low-income, treatment-resistant methadone patients. The treatment's central feature is an abstinence reinforcement contingency in which patients earn monetary reinforcement for providing cocaine-free urine samples. Success and failure of this contingency appear to be an orderly function of familiar parameters of operant conditioning. Increasing reinforcement magnitude and duration can increase effectiveness, and sustaining the contingency can prevent relapse. Initial development of a potentially practical application of this technology suggests that it may be possible to integrate abstinence reinforcement into employment settings using salary for work to reinforce drug abstinence. This research illustrates the potential utility and current limitations of an operant approach to the treatment of drug addiction. Similar research programs are needed to explore the limits of the operant approach and to develop practical applications that can be used widely in society for the treatment of drug addiction.     

Attendance Rates in A Workplace Predict Subsequent Outcome of Employment-Based Reinforcement of Cocaine Abstinence in Methadone Patients

This study assessed whether attendance rates in a workplace predicted subsequent outcome of employment-based reinforcement of cocaine abstinence. Unemployed adults in Baltimore methadone programs who used cocaine (N  =  111) could work in a workplace for 4 hr every weekday and earn $10.00 per hour in vouchers for 26 weeks. During an induction period, participants provided urine samples but could work independent of their urinalysis results. After the induction period, participants had to provide urinalysis evidence of cocaine abstinence to work and maintain maximum pay. A multiple regression analysis showed that induction period attendance was independently associated with urinalysis evidence of cocaine abstinence under the employment-based abstinence reinforcement contingency. Induction period attendance may measure the reinforcing value of employment and could be used to guide the improvement of employment-based abstinence reinforcement.     

A Web-Based Contingency Management Program With Adolescent Smokers

The present study evaluated a new 30-day Web-based contingency management program for smoking abstinence with 4 daily-smoking adolescents. Participants made 3 daily video recordings of themselves giving breath carbon monoxide (CO) samples at home that were sent electronically to study personnel. Using a reversal design, participants could earn money for continued abstinence during the treatment phases (CO ≤ 5 ppm). All participants were compliant with the treatment (submitting 97.2% of samples), and all achieved prolonged abstinence from smoking.     

Effects of time-based administration of abstinence reinforcement targeting opiate and cocaine use

Polydrug use is a common problem among patients in opioid-substitution treatment. Polydrug use has been reduced by administering abstinence-reinforcement contingencies in a sequence, such that a single drug is targeted until abstinence is achieved, and then an additional drug is targeted. The present study examined effects of administering abstinence-reinforcement contingencies sequentially based on time rather than on achieved abstinence. Participants accessed paid work (about $10/hr maximum) in the Therapeutic Workplace by providing urine samples 3 times per week. The urine samples were tested for opiates and cocaine. During an induction period, participants earned maximum pay independent of drug abstinence. Then, maximum pay depended upon urine samples that were negative for opiates. Two weeks later, maximum pay depended upon urine samples that were negative for both opiates and cocaine. Opiate and cocaine abstinence increased following administration of the respective contingencies. The time-based administration of abstinence reinforcement increased opiate and cocaine abstinence.     

The Relative Contribution of Economic Valence to Contingency Management Efficacy: A Pilot Study

We investigated the extent to which a contingency management (CM) procedure that deducted money from a grand total available at the end of the study compared to a procedure in which money accumulated with continued abstinence from cigarette smoking. Results suggested that the procedure in which money increased contingent on abstinence resulted in a significantly greater likelihood of obtaining a clinically relevant (i.e., 48-hr) period of abstinence. In terms of attendance, participants in the condition in which monetary reinforcement accrued with consecutive instances of abstinence were significantly less likely to miss consecutive appointments than those in which money was deducted for failure to abstain.     

EFFECT OF REINFORCEMENT PROBABILITY AND PRIZE SIZE ON COCAINE AND HEROIN ABSTINENCE IN PRIZE‐BASED CONTINGENCY MANAGEMENT

Although treatment outcome in prize‐based contingency management has been shown to depend on reinforcement schedule, the optimal schedule is still unknown. Therefore, we conducted a retrospective analysis of data from a randomized clinical trial (Ghitza et al., 2007) to determine the effects of the probability of winning a prize (low vs. high) and the size of the prize won (small, large, or jumbo) on likelihood of abstinence until the next urine‐collection day for heroin and cocaine users (N = 116) in methadone maintenance. Higher probability of winning, but not the size of individual prizes, was associated with a greater percentage of cocaine‐negative, but not opiate‐negative, urines.     

CONTINGENT REINFORCEMENT FOR BENZODIAZEPINE-FREE URINES: EVALUATION OF A DRUG ABUSE TREATMENT INTERVENTION

This study evaluated contingent reinforcement for benzodiazepine-free urines as a therapeutic intervention for promoting reduced use of supplemental benzodiazepine drugs among methadone maintenance outpatients. Ten methadone maintenance patients were selected for participation on the basis of positive urinalysis results. During a 12-week intervention period these patients were offered clinic privileges, including monetary payments or methadone take-home doses, contingent on benzodiazepine negative urinalysis test results. Eight of ten participants responded to the intervention with at least 2.5 weeks of consecutive clean urines. An increase in benzodiazepine-negative tests during the contingent reinforcement period was significant for the group as a whole. The results suggest that more widespread application of contingent reinforcement procedures may be warranted in drug abuse treatment clinics.     

VOUCHER‐BASED CONTINGENT REINFORCEMENT OF SMOKING ABSTINENCE AMONG METHADONE‐MAINTAINED PATIENTS: A PILOT STUDY

This study evaluated the efficacy of a contingency management (CM) intervention to promote smoking cessation in methadone‐maintained patients. Twenty participants, randomized into contingent (n = 10) or noncontingent (n = 10) experimental conditions, completed the 14‐day study. Abstinence was determined using breath carbon monoxide and urine cotinine levels. Contingent participants received voucher‐based incentives for biochemical evidence of smoking abstinence. Noncontingent participants earned vouchers independent of smoking status. Contingent participants achieved significantly more smoking abstinence and longer durations of continuous smoking abstinence than did noncontingent participants. These results support the potential efficacy of using voucher‐based CM to promote smoking cessation among methadone‐maintained patients.     

Comparing resetting to non‐resetting DRO procedures to reduce stereotypy in a child with autism

We compared a resetting to a non‐resetting differential reinforcement of other behavior (DRO) procedure to reduce stereotypy exhibited by young boy with autism. During the resetting DRO, a reinforcer was delivered contingent upon the absence of stereotypy during the DRO interval. If stereotypy occurred, the DRO interval was immediately reset. The non‐resetting DRO procedure was identical, except that contingent upon stereotypy, the DRO interval continued until it expired; a new DRO interval then began. Results indicate that the DRO procedures were equally effective to reduce stereotypy, but the participant preferred the resetting DRO procedure.     

A randomized trial of employment-based reinforcement of cocaine abstinence in injection drug users

High-magnitude and long-duration abstinence reinforcement can promote drug abstinence but can be difficult to finance. Employment may be a vehicle for arranging high-magnitude and long-duration abstinence reinforcement. This study determined if employment-based abstinence reinforcement could increase cocaine abstinence in adults who inject drugs and use cocaine during methadone treatment. Participants could work 4 hr every weekday in a workplace where they could earn about $10.00 per hour in vouchers; they were required to provide routine urine samples. Participants who attended the workplace and provided cocaine-positive urine samples during the initial 4 weeks were invited to work 26 weeks and were randomly assigned to an abstinence-and-work (n = 28) or work-only (n = 28) group. Abstinence-and-work participants had to provide urine samples showing cocaine abstinence to work and maintain maximum pay. Work-only participants could work independent of their urinalysis results. Abstinence-and-work participants provided more (p = .004; OR = 5.80, 95% CI = 2.03-16.56) cocaine-negative urine samples (29%) than did work-only participants (10%). Employment-based abstinence reinforcement can increase cocaine abstinence.     

Randomized Trial Comparing Two Treatment Strategies Using Prize-Based Reinforcement of Abstinence in Cocaine and Opiate Users

We compared two strategies of prize-based contingency management (CM) in methadone-maintained outpatients. Urine was tested thrice weekly for 5 weeks pre-CM, 12 weeks CM, and 8 weeks post-CM. Participants were randomly assigned to a cocaine contingency (four prize draws for each cocaine-negative urine, N  =  29) or an opiate-cocaine contingency (one draw for each urine negative for opiates or cocaine, four draws if negative for both, N  =  38). There were no group differences in cocaine abstinence during CM or post-CM and no differences in opiate abstinence during CM. Opiate abstinence was greater in the opiate-cocaine group post-CM, and heroin craving was reduced in this group during and post-CM. Draws earned per cocaine-negative urine (four vs. one) did not affect cocaine use.     

DIFFERENTIALLY REINFORCING LOW RATES OF MISBEHAVIOR WITH NORMAL ELEMENTARY SCHOOL CHILDREN1

Effective nonpunitive procedures for reducing counterproductive classroom behaviors are of potential benefit to both students and teachers. A recent strategy for dealing with this class of problem behaviors involves the reinforcement of acceptably low levels of such behavior. The laboratory version of this procedure, called differential reinforcement of low rates of responding (or DRL), provides for a reinforcer to be delivered contingent upon a response that is separated from the last preceding response by a minimum amount of time. To make this procedure more amenable to classroom use, the present authors have modified it so that a reinforcer is delivered if fewer than a specified number of responses occur within a preset time interval (Deitz and Repp, Journal of Applied Behavior Analysis, 1973, 6 , 457–463). Previous studies using this procedure have found it effective in reducing and maintaining low rates of targeted behaviors. However, these effects have been demonstrated with groups of subjects and/or individuals from dependent populations. The present study investigated use of this modified DRL procedure with individual students in normal elementary classrooms. In the first of three studies, “talk-outs” of an 11-yr-old fifth-grade male were reduced when nonexchangeable gold stars were made contingent on two or fewer responses per session. During baseline sessions, an average of 4.45 talkouts were observed per 45-min session. Average responding subsequently fell to 1.83 when the modified DRL contingency was applied, increased to 7.60 during a reversal phase, and dropped again to an average of 1.20 when the contingency was reapplied. In the second study, out-of-seat behavior of a 12-yr-old sixth-grade female was reduced when gold stars were made contingent on two or fewer responses per 45-min class period. Baseline responding averaged 6.10 responses per session. When the contingency was applied, average responding fell to 0.16. During the reversal period, responding increased to an average of 6.00 and fell again, after the contingency was re-introduced to an average of 0.40. In the third study, a reduction in both talking-out and out-of-seat behaviors of another 11-yr-old fifth-grade male was demonstrated with a multiple-baseline design. Using different lengths of baselines, gold stars were made contingent first on a low rate of out-of-seat behavior, and then on a low rate of talk-outs. Out-of-seat responding fell from a baseline average of 7.50 to a treatment average of 1.14. Talk-outs went from a baseline average of 4.66 to a treatment average of 1.14. In all three studies, the modified DRL procedure proved effective with the children and was manageable by the classroom teacher. For the students, nonexchangeable conditioned reinforcers (stars) were sufficient to maintain lowered rates of inappropriate behavior with the modified DRL schedule; there was no need for an elaborate token economy, a process that in many cases may be only a form of behavioral “overkill”. As in other studies investigating DRL schedules, students were not informed of their accumulation of responses; the differential effects of providing or withholding this feedback need to be investigated. Overall, these studies add single-subject replication with normal children to the literature on modified DRL procedures.     

Individual characteristics and response to Contingency Management treatment for cocaine addiction

Voucher-based contingency management (CM) research has demonstrated efficacy for treating cocaine addiction, but few studies have examined associations between individual baseline characteristics and response to CM treatments. The aim of this study, involving 50 cocaine outpatients receiving CM for cocaine addiction, was to assess the impact of baseline characteristics on abstinence outcomes after six months of treatment. Patients who were abstinent after six months of treatment accounted for 58% of the sample. Patients with higher scores on the Alcohol area of the EuropASI and patients that were non-abstinent during the first month of treatment were less likely to achieve abstinence. These outcome predictors have implications both for treatment research and for clinical practice. Patients who do not respond early to treatment may need a more intensive intervention, and concomitant problematic alcohol use should be detected and treated. The remaining baseline variables examined were not statistically significant predictors of abstinence. This finding is important for the generalizability of CM across the range of individual characteristics of treatment-seeking cocaine abusers.     

Interdependent Group Contingency Management for Cocaine-Dependent Methadone Maintenance Patients

Contingency management (CM) for drug abstinence has been applied to individuals independently even when delivered in groups. We developed a group CM intervention in which the behavior of a single, randomly selected, anonymous individual determined reinforcement delivery for the entire group. We also compared contingencies placed only on cocaine abstinence (CA) versus one of four behaviors (CA, treatment attendance, group CM attendance, and methadone compliance) selected randomly at each drawing. Two groups were formed with 22 cocaine-dependent community-based methadone patients and exposed to both CA and multiple behavior (MB) conditions in a reversal design counterbalanced across groups for exposure order. The group CM intervention proved feasible and safe. The MB condition improved group CM meeting attendance relative to the CA condition.     

Programming for Maintenance: An Investigation of Delayed Intermittent Reinforcement and Common Stimuli to Create Indiscriminable Contingencies

Generalization across time or maintenance of behavior change is a fundamental concern for behavior analysts and educators that remains insufficiently understood. This study examined the maintenance of mathematics responding during and following delayed intermittent reinforcement when common stimuli were programmed across the treatment and maintenance phases. Two third-grade girls who were referred by their classroom teacher due to concerns in the area of mathematics participated. Students were exposed to baseline, contingent reinforcement, delayed intermittent reinforcement, and a maintenance condition. The maintenance condition followed exposure to delayed intermittent reinforcement and included common stimuli from the reinforcement condition, but did not include a contingency for correct responding. Both students exhibited substantial prolonged maintenance during this condition. Implications of these results for future research examining maintenance and applied programming for maintenance are discussed.     

Satiation for social reinforcers: The effects of contingency,vicarious experience,and ambiguous situations

The relative satiation effect, an inverse relationship between the frequency of prior social reinforcement (the word “good”) and the later effectiveness of the social reinforcer in controlling behavior, was studied. In Experiment 1, a discrimination task in which social reinforcement was given for correct responses was administered to first- to fourth-grade children (6 to 10 years of age), who had during a preexposure phase performed a preliminary task or observed another child performing. During the preexposure phase, the experimenter delivered frequent or infrequent social reinforcement that was either contingent or noncontingent. Only performers and observers who had experienced frequent noncontingent reinforcement showed the satiation effect during the discrimination task phase. The results were interpreted as inconsistent with J. L. Gewirtz' (Developmental Psychology, 1969, 1, 2–13) social drive formulation but supportive of an informational analysis in which the children are seen as responding appropriately to unambiguous evidence concerning the reliability of contingency information. In Experiment 2, seating arrangements were varied so that information concerning the direction of reinforcement was made ambiguous. Performers were less responsive during the discrimination phase after experiencing frequent noncontingent reinforcement when seated alone or opposite an observer than when seated next to an observer. The results are interpreted as indicating trust of the reliability of the contingency under ambiguous conditions.     

Effects of escalating and descending schedules of incentives on cigarette smoking in smokers without plans to quit

Contingent incentives can reduce substance abuse. Escalating payment schedules, which begin with a small incentive magnitude and progressively increase with meeting the contingency, increase smoking abstinence. Likewise, descending payment schedules can increase cocaine abstinence. The current experiment enrolled smokers without plans to quit in the next 6 months and compared escalating and descending payments schedules over 15 visits. In the larger incentive condition (LI, n = 39), the largest possible incentive was $100, and in the smaller incentive condition (SI, n = 18), the largest possible incentive was $32. In both conditions, more participants in the descending groups initiated abstinence. A higher proportion of participants in both the escalating and descending groups initiated abstinence in the LI than in the SI. Although participants in the descending groups had more abstinent visits during the first five contingent visits than those in the escalating groups, these differences were not maintained.     

Motivational effects of smoked marijuana: behavioral contingencies and low-probability activities.

Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% delta 9-THC) or placebo were smoked during the private work period and the period of access to social activities. Three-day contingency conditions requiring subjects to engage in a low-probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high-probability work activity (contingent activity) were programmed during periods of placebo and active-marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low-probability instrumental activity and decreased the time spent engaged in the high-probability activity. During active-marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for "work activities."     

CONTINGENT REINFORCEMENT FOR CARBON MONOXIDE REDUCTION: WITHIN-SUBJECT EFFECTS OF PAY AMOUNT

The relationship between reinforcer amount and daytime smoking reduction in smokers offered money for reduced afternoon breath carbon monoxide (CO) levels was examined. Twenty-three hired regular smokers with average baseline CO levels of about 30 ppm were exposed in random order to five sliding scale payment schedules that changed daily or weekly. Money was available for afternoon CO readings between 0 and 21 ppm with pay amount inversely related to the absolute CO reading obtained. Maximum pay amount for readings below 7 ppm varied among $0, $1.50, $3, $6, and $12 per day. Contingent reinforcement promoted CO and daytime cigarette reduction within individuals with the amount of behavior change related to the amount of payment available. Average CO levels decreased from 30 to 15 ppm as a function of pay amount whereas self-reported daytime cigarettes decreased from 12 to 5 per day. Average minutes of cigarette abstinence prior to the afternoon study contact increased from 62 to 319 minutes as a function of pay amount, whereas the percentage of available money earned increased from 22% to 48%. Nontargeted evening cigarette use also decreased during periods of daytime smoking reduction. The orderly effects of this contingent reinforcement intervention on daytime smoking of regular smoker volunteers suggest that this is a sensitive model for continued evaluation of factors that influence smoking reduction and cessation.     

ALTERNATIVE REINFORCEMENT INCREASES RESISTANCE TO CHANGE: PAVLOVIAN OR OPERANT CONTINGENCIES?

Two multiple-schedule experiments with pigeons examined the effect of adding food reinforcement from an alternative source on the resistance of the reinforced response (target response) to the decremental effects of satiation and extinction. In Experiment 1, key pecks were reinforced by food in two components according to variable-interval schedules and, in some conditions, food was delivered according to variable-time schedules in one of the components. The rate of key pecking in a component was negatively related to the proportion of reinforcers from the alternative (variable-time) source. Resistance to satiation and extinction, in contrast, was positively related to the overall rate of reinforcement in the component. Experiment 2 was conceptually similar except that the alternative reinforcers were contingent on a specific concurrent response. Again, the rate of the target response varied as a function of its relative reinforcement, but its resistance to satiation and extinction varied directly with the overall rate of reinforcement in the component stimulus regardless of its relative reinforcement. Together the results of the two experiments suggest that the relative reinforcement of a response (the operant contingency) determines its rate, whereas the stimulus-reinforcement contingency (a Pavlovian contingency) determines its resistance to change.