Behavioral economics of drug self-administration. II. A unit-price analysis of cigarette smoking.

In behavioral economics, the ratio of response requirement to reinforcer magnitude is referred to as unit price. Previous research with nonhuman subjects has demonstrated that (a) comparable amounts of food are consumed at the same unit price even though different response requirements and reinforcer magnitudes comprise that unit price and (b) increases in unit price decrease food consumption in a positively decelerating fashion. The present study assessed the generality of these findings to the cigarette smoking of 5 human volunteers. During approximately 18 3-hr sessions, various combinations of response requirement (fixed-ratio 200, 400, and 1,600) and reinforcer magnitude (1, 2, and 4 puffs per bout) were arranged. Consumption (i.e., the number of puffs) generally was comparable at the same unit price independent of the response requirement and reinforcer magnitude comprising that unit price. In addition, increasing unit price generally decreased consumption in a positively decelerating fashion. These results extend the generality of the unit-price analysis to human cigarette smoking. Moreover, these results further support the position that reinforcer magnitude and response requirement are functionally equivalent and interact to determine consumption. The concept of unit price, by integrating and summarizing the effects of those two operations, provides a more parsimonious explanation of the results than do separate evaluations of the effects of response requirement and reinforcer magnitude.     

COMPARING TREATMENT TACTICS WITH A HYPERACTIVE PRESCHOOL CHILD: STIMULANT MEDICATION AND PROGRAMMED TEACHER INTERVENTION1

Two treatment tactics, food and praise contingent on appropriate play and varying doses of methylphenidate (Ritalin), were evaluated for their effects on a preschool child's activity changes. In addition, other social, verbal, and academic behaviors were monitored to examine possible side effects of the two treatment tactics. Fewer free-play activity changes occurred during contingent reinforcement phases while medication had variable effects: increasing attention to tasks but, at higher doses, decreasing intelligibility of speech and responsiveness to mands. The study outlines a replicable model for comparing medication with alternative behavioral strategies to control hyperactivity and enhance skill development.     

Separate neural sites for d-amphetamine suppression of mouse killing and feeding behavior in rats

The present study was conducted to investigate several possible neural sites for d-amphetamine's effect on mouse killing and feeding behaviors. d-Amphetamine (10, 20, and 30 μg) injected into each lateral ventricle, suppressed mouse kiling, food, and water intake in a dose-dependent manner. Bilateral adminstration of d-amphetamine (20 μg) into the central amygdaloid nucleus abolished mouse killing behavior but did not affect feeding and drinking. By contrast, bilateral amphetamine injections into the substantia nigra, or into the ventral region of the caudate nucleus, did not suppress mouse killing behavior, but significantly decreased food and water intake. The lateral hypothalamus was sensitive to d-amphetamine injections, which suppressed mouse killing and food intake as well as water intake. d-Amphetamine injections into the nucleus accumbens produced inconsistent effects on mouse killing and feeding. Our observations suggest a differentiation of the neural sites that mediate feeding from those underlying mouse killing behavior.     

Drug discrimination under concurrent variable-ratio variable-ratio schedules

Pigeons were trained to discriminate 5 mg/kg pentobarbital from saline under concurrent variable-ratio (VR) VR schedules, in which responses on the pentobarbital-biased lever were reinforced under the VR schedule with the smaller response requirements when pentobarbital was given before the session, and responses on the saline-biased key were reinforced under the VR schedule with the larger response requirements. When saline was administered before the session, the reinforcement contingencies associated with the two response keys were reversed. When responding stabilized under concurrent VR 20 VR 30, concurrent VR 10 VR 40, or concurrent VR 5 VR 50 schedules, pigeons responded almost exclusively on the key on which fewer responses were required to produce the reinforcer. When other doses of pentobarbital and other drugs were substituted for the training dose, low doses of all drugs produced responding on the saline-biased key. Higher doses of pentobarbital and chlordiazepoxide produced responding only on the pentobarbital-biased key, whereas higher doses of ethanol and phencyclidine produced responding only on this key less often. d-Amphetamine produced responding primarily on the saline-biased key. When drugs generalized to pentobarbital, the shape of the generalization curve under concurrent VR VR schedules was more often graded than quantal in shape. Thus, drug discrimination can be established under concurrent VR VR schedules, but the shapes of drug-discrimination dose-response curves under concurrent VR VR schedules more closely resemble those seen under interval schedules than those seen under fixed-ratio schedules. Graded dose-response curves under concurrent VR VR schedules may relate to probability matching and difficulty in discriminating differences in reinforcement frequency.     

Family-Based Therapy for Adolescent Drug Abuse: Knowns and Unknowns

Family-based therapy is one of the most thoroughly studied treatments for adolescent drug abuse. Considerable empirical support exists for the efficacy of family-based therapy in curtailing adolescent drug use and cooccurring behavior problems. This article extends knowledge of the effects of family-based therapy for adolescent drug abuse by reviewing 16 controlled trials and 4 therapy process studies from a treatment development perspective. We articulate knowns and unknowns regarding the outcomes of treatment as well as the components, processes, mechanisms, moderators, and boundaries of effective family-based therapy for adolescent drug abuse. The review highlights areas of progress and future research needs within the specialty of family-based therapy for adolescent drug abuse.     

The concept of placebo

This paper attempts to define the concept of placebo as it is used in the clinical context The author claims that X is a placebo if and only if X has such a property d_p, that whenever in a therapeutic situation T a stimulus S appears, then in attending conditions A, it will cause a beneficial reaction R in the patient. Formally, the same structure may be used to define any pharmacologically active drug. The main difference between the drug and a placebo is in the range of possible substitutions for X and the property d. For the active drug there is only one possible substitution for X and property d and it can be scientifically explained why, and how the drug works. In the case of a placebo a set of possible substitutions for X and d is open, and so far it is impossible to offer any scientifically valid explanation of the action mechanism of placebo.     

Behavioral and pharmacological variables affecting risky choice in rats.

The effects of manipulations of response requirement, intertrial interval (ITI), and psychoactive drugs (ethanol, phencyclidine, and d-amphetamine) on lever choice under concurrent fixed-ratio schedules were investigated in rats. Responding on the "certain' lever produced three 45-mg pellets, whereas responding on the "risky" lever produced either 15 pellets (p = .33) or no pellets (p .67). Rats earned all food during the session, which ended after 12 forced trials and 93 choice trials or 90 min, whichever occurred first. When the response requirement was increased from 1 to 16 and the ITI was 20 s, percentage of risky choice was inversely related to fixed-ratio value. When only a single response was required but the ITI was manipulated between 20 and 120 s (with maximum session duration held constant), percentage of risky choice was directly related to length of the ITI. The effects of the drugs were investigated first at an ITI of 20 s, when risky choice was low for most rats, and then at an ITI of 80 s, when risky choice was higher for most rats. Ethanol usually decreased risky choice. Phencyclidine did not usually affect risky choice when the ITI was 20 s but decreased it in half the rats when the ITI was 80 s. For d-amphetamine, the effects appeared to he related to baseline probability of risky choice; that is, low probabilities were increased and high probabilities were decreased. Although increase in risky choice as a function of the ITI is at variance with previous ITI data, it is consistent with foraging data showing that risk aversion decreases as food availability decreases. The pharmacological manipulations showed that drug effects on risky choice may be influenced by the baseline probability of risky choice, just as drug effects can be a function of baseline response rate.     

Drug discrimination under a concurrent fixed-ratio fixed-ratio schedule.

Pigeons were trained to discriminate 5.0 mg/kg pentobarbital from saline under a two-key concurrent fixed-ratio 10 fixed-ratio 40 schedule of food presentation, in which the fixed-ratio component with the lower response requirement was programmed to reinforce responding on one key after drug administration (pentobarbital-biased key) and on the other key after saline administration (saline-biased key). After responding stabilized, pigeons averaged 98% of their responses on the pentobarbital-biased key during training sessions preceded by pentobarbital, and they averaged 90% of their responses on the saline-biased key during training sessions preceded by saline. In test sessions preceded by doses of pentobarbital, chlordiazepoxide, or ethanol, pigeons switched from responding on the saline-biased key at low doses to responding on the pentobarbital-biased key at higher doses (the dose-response curve was quantal). High doses of phencyclidine produced responding on both keys, whereas pigeons responded almost exclusively on the saline-biased key after all doses of methamphetamine. These and previous experiments using concurrent reinforcement schedules to study drug discrimination illustrate that the schedule of reinforcement is an important determinant of the shape of dose-effect curves in drug-discrimination experiments.     

Drug Use Among Immigrant and Non‐immigrant Adolescents: Immigrant Paradox,Family and Peer Influences

The present study compared immigrant and Italian native adolescents with regard to drug use. Additionally, we analysed the role of family and peer risk and protective factors for drug use. Participants included 2533 Italian native and immigrant adolescents (mean age = 17.19, SD = 1.6; 66.7% male). Results showed that immigrant adolescents reported lower levels of marijuana and pharmaceutical drug abuse than non‐immigrant adolescents. These results confirm the so‐called immigrant paradox phenomenon: the counterintuitive finding that although immigrants often live under challenging conditions and reported lower economic affluence compared with nationals, some health outcomes have not always corresponded to their relative disadvantage. Immigrant adolescents also reported higher level of parental control and lower levels of affiliation with deviant peers, but lower levels of child disclosure, parental solicitation and parental knowledge. Socio‐economic status and parental monitoring showed equivalent effects on drug use for immigrant and non‐immigrant adolescents. Results have implications for preventive interventions for immigrant adolescents and families, including the need to develop programmes that leverage the benefits of the immigrant paradox for immigrant communities. Future research should analyse the processes that lead to lower levels of drug use in immigrant adolescents and investigate the influence of friendship networks on immigrant adolescent drug use behaviour. Copyright © 2015 John Wiley & Sons, Ltd.