Noncontingent Group Research Articles

Physiological characterization of instrumental learning in the spinal cord using the Paw Withdrawal Learning paradigm

Following spinal cord injury (SCI), sensory and motor functions are severely disrupted yet the spinal circuitry below the injury site continues to maintain active and functional neuronal properties (Edgerton, 2004). The spinal cord is endogenously capable of several forms of adaptive plasticity, including functional re-training with exercise, instrumental, and Pavlovian learning. The paw withdrawal learning (PaWL) paradigm represents a simple spinal instrumental learning model (Jindrich 2019). Briefly, in mice whose spinal cords are completely transected (ST) at mid-thoracic (T7-T9) level, the tibialis anterior (TA) muscle is given a sub maximal threshold shock to a hind leg when the leg is extended below a 1mm imposed threshold from a baseline starting position. The contingent group mice learn to maintain the shocked leg, in a flexed position while the experimentally coupled noncontingent group of mice do not acquire the flexed position. To demonstrate the acquisition of the flexed paw hold is mediated through muscle-specific proprioceptive inputs and a time dependent modification of the spinal interneuronal network associated with the TA motor pool, we measured the TA muscle activity using acute EMG during PaWL in both Contingent stim and non-contingent stim groups. To demonstrate that TA specific sensory afferents are critical in PaWL, we blocked the proprioceptive muscle and the cutaneous afferents using Lidocaine. During PaWL, the TA muscle showed significant EMG activity when compared to medial gastrocnemius and vastus lateralis muscles. We detected greater TA muscle activity in the Contingent stim compared to the non-contingent groups. The significant increase in the EMG amplitude in the TA muscle and time-frequency and power relationships in the contingent group, but not the non-contingent group, suggests that the successful learning requires a temporal engagement of the spinal sensorimotor network. CSULA Mini-Grant 2020 and Joseph/Gomez-Pinilla R01NS056413 (Diversity Supplement) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Improvements in Middle-Schoolers’ Performance and Motivation to Practice: An Experimental Investigation of Accurate Feedback in a Motor Task

The present field experiment investigated the effects of accurate and non-accurate performance feedback on causal attributions, success expectancy, performance, and persistence on a motor task. Forty-six male middle-schoolers were randomly assigned to a Contingent (accurate) feedback, Non-contingent (non-accurate) feedback, or Control (no feedback) group and completed a challenging motor task. An initial treatment phase provided either accurate contingent feedback or yoked non-contingent feedback during the task, and measured task performance, attributions about performance, and success expectancy about future performance. A subsequent testing phase (same task) used the same measures and added a measure of motivation (persistence). Compared to the Contingent and Control groups, Noncontingent outcome feedback during the initial treatment phase led to more personally uncontrollable attributions, lower success expectancy, poorer performance, and lower persistence in the subsequent test phase. Despite a high rate of failure in the motor task for both feedback groups in the treatment phase, the Contingent group—getting accurate feedback about performance—had a higher sense of personal control and expectancy of success than the Non-contingent feedback group initially, and maintained these perceptions in the subsequent test phase where they also had better performance and higher levels of persistence than the Non-contingent group. Non-contingent feedback in an initial motor task appears to induce helplessness deficits in subsequent task performance and persistence. In contrast, providing accurate (contingent) feedback about achieved performance appears to protect against performance and motivational losses.

Remotely administered incentive-based treatment for alcohol use disorder with participant-funded incentives is effective but less accessible to low-income participants.

The delivery of monetary incentives contingent on verified abstinence is an effective treatment for alcohol use disorder. However, incentive cost has often been cited as a barrier to delivering this type of treatment. In the present randomized parallel groups trial, we systematically replicated a previous trial we conducted that employed remote alcohol monitoring and incentive delivery to promote abstinence from alcohol, but with the additional requirement for participants to partially self-fund their abstinence incentives. Treatment-seeking participants with alcohol use disorder (n = 92) who met inclusion criteria (n = 36) were randomized to either a Contingent or Noncontingent group (n = 18 each). Those not meeting inclusion criteria included 15 participants who agreed to the deposit requirement but failed to make the deposit payment. The Contingent group received nearly immediate monetary incentives each day they remotely provided negative breathalyzer samples. The Noncontingent group received matched incentives each day they successfully provided samples independent of alcohol content. Days abstinent in the Contingent group were 86%, which was significantly higher than the 44% recorded in the Noncontingent group, corresponding to an odds ratio of 8.2. Exploratory analyses revealed that the deposit requirement prevented participation in those with lower incomes and those with greater alcohol use. These results support the efficacy of this remotely deliverable alcohol abstinence reinforcement incentive intervention with a deposit requirement. However, the requirement to provide a monetary deposit to self-fund abstinence incentives may prevent those with greater alcohol use and/or those experiencing extreme poverty from participating in the intervention. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Do 12-month-old infants maintain expectations of contingent or non-contingent responding based on prior experiences with unfamiliar and familiar adults?

Abstract The current study examined whether infants use previous encounters for maintaining expectations for adults’ contingent responding. An unfamiliar adult responded contingently or non-contingently to infant signaling during an initial play situation and 10 min later presented an ambiguous toy while providing positive information (Experiment 1; forty-two 12-month-olds). The infants in the contingent group looked more at the adult during toy presentation and played more with the toy during the concluding free-play situation than the infants in the non-contingent group. When the parent had responded contingently or non-contingently to infant bids (Experiment 2; forty 12-month-olds), the infants in the contingent group tended to look more at the parent and tended to play more with the toy than did the infants in the non-contingent group. The results indicate that from just a brief exposure, infants form expectations about adults’ responsiveness and maintain these expectations of contingent/non-contingent responding from one situation to another.

Female Social Feedback Reveals Non-imitative Mechanisms of Vocal Learning in Zebra Finches

Learning of song in birds provides a powerful model for human speech development [1-3]. However, the degree to which songbirds and humans share social mechanisms of vocal learning is unknown. Although it has been demonstrated as a vocal learning mechanism in human infants [3-6], learning via active social feedback is considered rare and atypical among non-human animals [7]. We report here the first evidence that song learning in the zebra finch (Taeniopygia guttata), the most common model species of vocal learning and development, utilizes socially guided vocal learning. We demonstrate experimentally that the songs of juvenile zebra finches areguided toward mature vocal forms by real-time visual feedback from adult females that is contingent ontheir early, immature vocalizations. Using a video playback paradigm, we found that juvenile birds that received non-vocal female feedback contingently ontheir immature song learned significantly better and more accurate song than did yoked controls that received identical but non-contingent feedback.Both contingent and non-contingent groups sang at similar rates. Thus, we have provided the firstevidence suggesting that non-imitative social learning is a crucial, potentially widespread mechanism of vocal development and have established afoundational parallel between humans and our most ubiquitous animal model of vocal learning: the crucial role of social feedback to immature vocalizations in the development of communication.

Computerized Exposure Therapy for Spider Phobia: Effects of Cardiac Timing and Interoceptive Ability on Subjective and Behavioral Outcomes.

Spider phobia is a common form of anxiety disorder for which exposure therapy is an effective first-line treatment. Motivated by the observed modulation of threat processing by afferent cardiac signals, we tested the hypothesis that interoceptive information concerning cardiovascular arousal can influence the outcomes of computerized exposure therapy for spider phobia. Fifty-three normal healthy participants with high spider phobia scores underwent one of the following three modified computerized exposure protocols, defined by the timing of exposure to brief spider stimuli within the cardiac cycle: systole (during afferent baroreceptor firing); diastole (during baroreceptor-quiescent interbeat interval); random (noncontingent on cardiac cycle). Outcomes were judged on phobic and anxiety measures and physiological data (skin conductance). Individuals were also rated on interoceptive accuracy. MANCOVA analysis showed that timing group affected the outcome measures (F(10,80) = 2.405, p = .015) and there was a group interaction with interoception ability (F(15,110) = 1.808, p = .045). Subjective symptom reduction was greatest in the systolic group relative to the other two groups (diastolic (t = 3.115, ptukey = .009); random (t = 2.438, ptukey = .048)), with greatest reductions in those participants with lower interoceptive accuracy. Behavioral aversion reduced more in cardiac-contingent groups than the noncontingent (random) group (diastolic (t = 3.295, ptukey = .005); systolic (t = 2.602, ptukey = .032)). Physiological (skin conductance response) responses remained strongest for spider stimuli presented at cardiac systole. Interoceptive information influences exposure benefit. The reduction in the subjective expression of fear/phobia is facilitated by "bottom-up" afferent signals, whereas improvement in the behavioral expression is further dependent on "top-down" representation of self-related physiology (heart rhythm). Individual interoceptive differences moderate these effects, suggesting means to personalize therapy.

Developmental Manipulations of Female Social Feedback Reveal Nonimitative Mechanisms of Vocal Learning in Songbirds

Learning of song in birds provides a powerful model for human speech development. However, the degree to which songbirds and humans share social mechanisms of vocal learning is unknown. Although it has been demonstrated as a vocal learning mechanism in human infants, learning via active social feedback is considered rare and atypical among non-human animals. We report here the first evidence that song learning in the zebra finch (Taeniopygia guttata), the most common model species of vocal learning and development, utilizes socially guided vocal learning. We demonstrate experimentally that the songs of juvenile zebra finches are guided towards mature vocal forms by real-time visual feedback from adult females that is contingent on their early, immature vocalizations. Using a video playback paradigm, we found that juvenile birds that received non-vocal female feedback contingently on their immature song learned significantly better and more accurate song than did yoked controls that received identical but non-contingent feedback. Both contingent and non-contingent groups sang at similar rates. Thus we have provided the first evidence suggesting that non-imitative social learning is a crucial, potentially widespread mechanism of vocal development, and have established a foundational parallel between humans and our most ubiquitous animal model of vocal learning – the crucial role of social feedback to immature vocalizations in the development of communication.

Remote Alcohol Monitoring to Facilitate Incentive-Based Treatment for Alcohol Use Disorder: A Randomized Trial.

BackgroundThe delivery of monetary incentives contingent on verified abstinence is an effective treatment for alcohol use disorder. However, technological barriers to accurate, frequent biochemical verification of alcohol abstinence have limited the dissemination of this technique.MethodsIn the present randomized parallel trial, we employed a breathalyzer that allows remote, user‐verified collection of a breath alcohol sample, text messaging, and reloadable debit cards for remote delivery of incentives to evaluate a contingency management treatment for alcohol use disorder that can be delivered with no in‐person contact. Treatment‐seeking participants with alcohol use disorder (n = 40) were recruited from the community and randomized to either a contingent or a noncontingent group (n = 20 each). The contingent group received nearly immediate monetary incentives each day they remotely provided negative breathalyzer samples. The noncontingent group received matched monetary payments each day they successfully provided samples independent of alcohol content. Groups were not masked as awareness of group contingencies was an essential intervention component.ResultsThe primary outcome of the intent‐to‐treat analyses (analyzed n = 40) was percent days abstinent as measured by the remote breathalyzer samples. Abstinence rates in the contingent group were 85%, which was significantly higher than the 38% recorded in the noncontingent group, corresponding to an odds ratio of 9.4 (95% CI = 4.0 to 22.2). Breathalyzer collection adherence rates were over 95%, and participant ratings of acceptability were also high.ConclusionsThese results support the efficacy, acceptability, and feasibility of this remotely deliverable abstinence reinforcement incentive intervention for the initiation and near‐term maintenance of abstinence from alcohol in adults with alcohol use disorder. Due to low provider and participant burden, this procedure has the potential for broad dissemination.

Waterpipe Tobacco Cessation

Background: Waterpipe smoking contains carcinogens and toxicants such as tobacco nitrosamines and heavy metals. To date, few smoking cessation interventions targeting waterpipe tobacco smoking have been reported worldwide. The most recent Cochrane review emphasized the need for evidence on hookah tobacco use interventions since only a few trials of sufficient quality have been published. Aim: The objective of this randomized clinical trial was to examine the efficacy of contingency management (CM) for promoting initial waterpipe smoking abstinence. Methods: Thirty-nine adults completed the study. Participants were adults 18 years of age and older who smoked tobacco using a waterpipe three times or more per week for the past one year, did not smoke cigarettes, and were not planning on quitting waterpipe tobacco smoking. A two-group, repeated measures (10 study visits on Mondays and Thursdays) design was used. Participants were randomly assigned to either the contingent (n = 19) or noncontingent (n = 20) study arms. The primary study outcomes were biochemically verified prolonged abstinence and 7-day point prevalence. Results: The prolonged abstinence rate in the contingent and noncontingent groups were 42.1% and 5.0%, respectively, ( P = 0.008). The 7-day point prevalence in the contingent and noncontingent were 47.4% and 5.0%, respectively, ( P = 0.003). Conclusion: Rewards contingent on biochemically verified abstinence promote initial waterpipe tobacco cessation. This is useful information for consideration in future cessation programs for waterpipe smokers.

Comparison of the Time-Dependent Changes in Immediate Early Gene Labeling and Spine Density Following Abstinence From Contingent or Non-contingent Chocolate Pellet Delivery.

Rationale: Incubation of craving is a phenomenon whereby responding for cues associated with a reward increases over extended periods of abstinence. Both contingent and non-contingent behavioral designs have been used to study the incubation of craving phenomenon with differing results. The present study directly compares behavioral and neural changes following contingent or non-contingent administration of chocolate flavored pellets.Objective: The current study examined whether an incubation of craving response would be observed at the behavioral and neural levels following delays of abstinence from chocolate pellets in a contingent or non-contingent reinforcement design.Methods: Rats were trained for 10 days to bar press for chocolate pellets (contingent) or received chocolate pellets in a non-contingent design (classical conditioning). Groups were then subjected to abstinence from the reward for 24 h, 7, 14 or 28 days at which point they were tested for responding for reward associated cues. Following the test, brains from all rats were processed and assessed for c-Fos and FosB labeling as well as dendritic spine density in the nucleus accumbens (NAc).Results: Behavioral measures during the test (lever presses, food hopper entries and locomotor activity) revealed similar behavioral outcomes across all delays indicating the lack of an incubation of craving response on both the contingent and non-contingent designs. Overall, labeling of c-Fos in the NAc was lower for the non-contingent group compared to the operant-trained and food restricted control. Compared to the operant-trained and non-trained control groups, a significantly reduced FosB labeling was noted in the NAc of the classically conditioned groups across all abstinence periods. Spine density in the NAc was elevated in both the classically and operant conditioned compared to the food-restricted, non-trained controls.Conclusions: Chocolate pellet reward did not result in incubation of craving but did produce behavioral learning that was associated with increased spine density. This suggests that chocolate pellet administration results in long-term structural and functional changes that are present for at least 28 days following abstinence. Contingent and non-contingent administration resulted in differential immediate early gene labeling in the NAc, but the functional significance of this has yet to be elucidated.

A randomized clinical trial to evaluate the efficacy of contingency management for treatment of waterpipe tobacco addiction.

Unlike cigarette smoking cessation, waterpipe tobacco smoking cessation is relatively understudied. The objective of this randomized clinical trial was to examine the efficacy of contingency management (CM) for promoting initial waterpipe smoking abstinence. The study used a two-group, repeated measures design. Participants attended 10 visits (two visits per week, on Mondays and Thursdays) across 5 weeks. Thirty-nine adult waterpipe tobacco users who did not smoke cigarettes and were not planning on quitting waterpipe tobacco smoking were randomly assigned to either the contingent (n = 19) or non-contingent (n = 20) groups. Contingent group received monetary rewards based on negative salivary cotinine results. Earning rewards started at $14 and increased by $.50 with each subsequent negative sample for a maximum $192.50. Non-contingent group earned rewards independent of salivary cotinine results. Prolonged abstinence was defined as having negative salivary cotinine results for eight or more visits (two lapses were allowed); and 7-day point prevalence was defined as having negative salivary cotinine results at visit 9 and 10 (final week). The prolonged abstinence rate in the contingent and non-contingent groups were 42.1% and 5.0%, respectively, (p = .008). The 7-day point prevalence in the contingent and non-contingent were 47.4% and 5.0%, respectively, (p = .003). Rewards contingent on biochemically verified abstinence promote initial waterpipe tobacco cessation. This is useful information for consideration in future cessation programs for waterpipe smokers. CM strategy may have potential benefit in addressing waterpipe tobacco smoking in non-treatment seeking adults. (Am J Addict 2018;27:202-209).

Saliva Cotinine as a Measure of Smoking Abstinence in Contingency Management – A Feasibility Study

The present study investigated the feasibility of using twice-weekly monitoring of saliva cotinine in a prize-based contingency-management program for smoking cessation. Saliva samples were tested using semi-quantitative NicAlert™ cotinine test strips. Smokers (N = 20) who reported smoking at least five cigarettes per day were randomly assigned to either a contingent or a non-contingent reinforcement group. A five-day baseline phase was followed by a four-day shaping phase during which participants were asked to gradually decrease smoking. During the subsequent three-week abstinence phase, participants submitted breath CO and saliva samples twice per week. For those in the contingent reinforcement group, prize draws could be earned for negative samples or, on the first day of the abstinence phase and after a relapse, for saliva samples one semi-quantitative level below the previous sample. On each visit participants in both groups were given feedback on their saliva cotinine and breath CO levels, and were given instructions for how much to reduce smoking in order to meet the next smoking criteria. Saliva cotinine measures significantly correlated with breath CO measures and aligned with self-reports of smoking. Attendance in both groups decreased after the shaping phase. Cotinine and CO levels decreased in participants, but there were no significant group differences. Although the present study failed to demonstrate a treatment effect for the prize contingency (possibly due to the relatively low net payment), it appeared that using NicAlert™ saliva cotinine test strips was a relatively easy and effective way to monitor smoking throughout a contingency-management program.

Internet-based incentives increase blood glucose testing with a non-adherent, diverse sample of teens with type 1 diabetes mellitus: a randomized controlled Trial.

Non-adherence with self-monitoring blood glucose (SMBG) among teenagers with type 1 diabetes can be a problem. The purpose of this study was to investigate the feasibility, acceptability, and preliminary efficacy of using Internet-based incentives to improve adherence with SMBG in non-adherent teenagers. Participants were randomly assigned to contingent (CS; N = 23), where they had to meet web camera-verified SMBG goals to earn incentives, or non-contingent (NS) groups (N = 18), where they earned incentives independent of adherence. Brief motivational interviewing (MI) was given prior to the intervention. Attrition was 15% in the CS group. Participants and parents endorsed the intervention on all intervention dimensions. Daily SMBG increased after one MI session, and further increased when incentives were added, but significantly more for so for older participants. SMBG declined slowly over time, but only returned to baseline levels for younger NS participants. Internet-based incentive interventions are feasible, acceptable, and show promise for improving adherence with SMBG.

Internet-based contingency management to promote smoking cessation: A randomized controlled study

We evaluated an Internet-based contingency management intervention to promote smoking cessation. Participants in the contingent group (n = 39) earned vouchers contingent on video confirmation of breath carbon monoxide (CO) ≤ 4 parts per million (ppm). Earnings for participants in the noncontingent group (n = 38) were independent of CO levels. Goals and feedback about smoking status were provided on participants' homepages. The median percentages of negative samples during the intervention in the noncontingent and contingent groups were 25% and 66.7%, respectively. There were no significant differences in absolute CO levels or abstinence at 3- and 6-month follow-ups. Compared to baseline, however, participants in both groups reduced CO by an estimated 15.6 ppm during the intervention phases. The results suggest that the contingency for negative COs promoted higher rates of abstinence during treatment, and that other elements of the system, such as feedback, frequent monitoring, and goals, reduced smoking.

Effort-Based Reward (EBR) training enhances neurobiological efficiency in a problem-solving task: Insights for depression therapies

Effort-Based Reward (EBR) training strengthens associations between effort and rewards, leading to increased persistence in an unsolvable task when compared to control animals. EBR training involves placing animals in a test apparatus in which they are trained to dig in mounds to retrieve froot loop rewards (contingent group); these animals are compared to control animals that are given the same number of rewards, regardless of expended effort (noncontingent group). In the current study, the effect of EBR training on performance in a spatial task (Dry Land Maze) was explored to determine cognitive resilience during behavioral testing. Additionally, animals received BrdU injections during training to assess the role of neurogenesis on subsequent behavioral performance. Following the probe test, animals were perfused so that fos-immunoreactive (ir) cells in the hippocampus and cortical areas could be assessed. Behavioral results indicated that contingent rats were approximately 50% more efficient in locating and interacting with the previous baited well during the probe test than noncontingent animals, recruiting approximately 20% less c-fos ir-cells in the insular cortex, retrosplenial cortex, and dentate gyrus. A multidimensional scaling analysis grouped noncontingent animals together in a quadrant characterized by high latencies to find the previous baited well and higher ir-cell activation in the aforementioned areas. Thus, our data support the hypothesis that the EBR training enhances both cognitive functioning and emotional regulation during challenging events. Considering the ongoing controversy about the efficacy of pharmacological interventions in treating depression, the EBR model provides a valuable alternative for the investigation of the neurobiology of mood disorders.

Contingency is Crucial for Creating Imitative Responses

Contingency is Crucial for Creating Imitative Responses

Contingency management for behavior change: applications to promote brief smoking cessation among opioid-maintained patients.

Cigarette smoking is highly prevalent among patients who are being treated for opioid-dependence, yet there have been limited scientific efforts to promote smoking cessation in this population. Contingency management (CM) is a behavioral treatment that provides monetary incentives contingent upon biochemical evidence of drug abstinence. This paper discusses the results of two studies that utilized CM to promote brief smoking cessation among opioid-maintained patients. Participants in a pilot study were randomly assigned for a 2-week period to a Contingent group that earned monetary vouchers for providing biochemical samples that met criteria for smoking abstinence, or a Noncontingent group that earned monetary vouchers independent of smoking status (Dunn et al., 2008). Results showed Contingent participants provided significantly more smoking-negative samples than Noncontingent participants (55% vs. 5%, respectively). A second randomized trial that utilized the same 2-week intervention and provided access to the smoking cessation pharmacotherapy bupropion replicated the results of the pilot study (55% and 17% abstinence in Contingent and Noncontingent groups, respectively; Dunn et al, 2010). Relapse to illicit drug use was also evaluated prospectively and no association between smoking abstinence and relapse to illicit drug use was observed (Dunn et al., 2009). It will be important for future studies to evaluate participant characteristics that might predict better treatment outcome, to assess the contribution that pharmacotherapies might have alone or in combination with a CM intervention on smoking cessation and to evaluate methods for maintaining the abstinence that is achieved during this brief intervention for longer periods of time.

Alterations of prodynorphin gene expression in the rat mesocorticolimbic system during heroin self-administration

Opiate-induced alterations in the gene expression of the opioid propeptides prodynorphin (PDYN) and proenkephalin (PENK) in the brain have previously been described. However, there are no studies examining opioid propeptide system alterations due to long-lasting heroin self-administration. In our study, using in situ hybridization, we measured PDYN and PENK mRNA levels in the dorsal striatum, central nucleus of amygdala (CEA), and nucleus accumbens (NAcc) shell and core in rats after 6 weeks of heroin self-administration (fixed ratio 5, 0.02 mg/kg/infusion of heroin i.v.) and their respective saline or heroin “yoked” control. Our results show an increase in the PDYN mRNA level in the CEA and NAcc shell and no changes of PENK gene expression after heroin self-administration. In addition, to dissociate pharmacological effects of heroin from those produced by motivational processes driving active heroin intake on the PDYN and PENK gene expression, we compared effects of response-dependent (contingent) and response-independent (noncontingent — “yoked” heroin control) heroin administration. We found no differences between contingent and noncontingent groups of rats. In conclusion, our results indicate neuroadaptations in the PDYN but not PENK gene expression in rat limbic forebrain during heroin self-administration. We show that such changes depend on direct pharmacological actions of heroin rather than contingent heroin intake. These neuroalterations probably occur as an adaptation to long-lasting heroin exposure and may underlie changes leading to compulsive drug use and addiction.

Randomized trial of prize-based reinforcement density for simultaneous abstinence from cocaine and heroin.

To examine the effect of reinforcer density in prize-based abstinence reinforcement, heroin/cocaine users (N = 116) in methadone maintenance (100 mg/day) were randomly assigned to a noncontingent control group (NonC) or to 1 of 3 groups that earned prize draws for abstinence: manual drawing with standard prize density (MS) or computerized drawing with standard (CS) or high (CH) density. Probabilities (prizes/draw) were standard (50%) and high (78%); prize density was double blind. Mean prize values were CH, $286; CS, $167; MS, $139; and NonC, $171. Outcomes were % opioid/cocaine-negative urines during the 12-week intervention and then 8 weeks postintervention as well as diagnosis of dependence up to 6 months poststudy. CH had significantly more negative specimens than did NonC during intervention and had more than all groups during postintervention treatment: Mean % negative (95% confidence interval) during postintervention treatment adjusted for baseline drug use and dropout were CH, 55% (14%-90%); CS, 7% (1%-27%); MS, 4% (1%-12%); and NonC, 3% (1%-10%). Current cocaine dependence diagnoses after treatment were significantly lower in contingent compared with noncontingent groups. Computerized drawing with higher-density prizes enhanced reduction of cocaine use; abstinence reinforcement had long-term therapeutic benefits.

Effectiveness of Payment for Reduced Carbon Monoxide Levels and Noncontingent Payments on Smoking Behaviors in Cocaine-Abusing Outpatients Wearing Nicotine or Placebo Patches.

In a 2-week intervention to reduce cigarette smoking among outpatients in treatment for cocaine addiction, 20 subjects were randomly assigned to a contingent group, receiving monetary vouchers for breath samples with carbon monoxide (CO) levels of 8 ppm or less, or to a noncontingent group, receiving vouchers regardless of CO level. Subjects wore either nicotine or placebo patches in a randomized crossover design. Contingent subjects had significantly lower CO levels and met the 8 ppm target significantly more often than did noncontingent subjects; however, number of cigarettes reported smoked did not differ between groups. Use of nicotine patches resulted in CO levels significantly lower than did use of placebo patches, but levels still exceeded 8 ppm regardless of type of patch. Because contingent reward helped cocaine-dependent smokers achieve nonsmoking CO targets, behavioral antismoking interventions merit continued study in similar populations.