PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Reinforcement Schedule”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources
PubMed2002

Failure of a reinforced triple course of hepatitis B vaccination in patients transplanted for HBV-related cirrhosis.

Long-term immunoprophylaxis with anti-HBs immunoglobulins (HBIg) is used to prevent hepatitis B (HBV) reinfection after liver transplantation for HBV-related cirrhosis. This approach is highly expensive. A recent report proposed posttransplant HBV vaccination with a reinforced schedule as an alternative strategy to allow HBIg discontinuation. We investigated the efficacy of a reinforced triple course of HBV vaccination in 17 patients transplanted for HBsAg-positive cirrhosis 2 to 7 years earlier. The first cycle consisted of 3 double intramuscular doses (40 microg) of recombinant vaccine at month 0, 1, and 2, respectively. This was followed, in nonresponders, by a second cycle of 6 intradermal 10 microg doses every 15 days. All nonresponders then received a third cycle identical to the first one. Vaccination started 4.5 months after HBIg discontinuation, and lamivudine (100 mg/day) was given throughout the study. All patients were seronegative for HBsAg and HBV-DNA (by PCR) and positive for anti-HBe, and 7 were positive for anti-HDV. After the first cycle one patient (#5, 53 years old, male) developed an anti-HBs titer of 154 IU/L, another (#12) reached a titer of 20 IU/L and the remainder had titers <10 IU/L. At month 7, patient #5 reached a titer of 687 IU/L. After the second cycle only one additional patient (#9) had a slight response (an anti-HBs titer of 37 IU/L). After the third cycle patient #9 rose to an anti-HBs titer of 280 IU/L, patient #12 dropped to 10 IU/L, and no other patient responded. In conclusion, a highly reinforced HBV vaccination program is effective only in a few patients who had liver transplants for HBV-related cirrhosis.

Adult↗
PubMed1998

Comparative learning theory and its application in the training of horses.

Training can best be explained as a process that occurs through stimulus-response-reinforcement chains, whereby animals are conditioned to associate cues in their environment, with specific behavioural responses and their rewarding consequences. Research into learning in horses has concentrated on their powers of discrimination and on primary positive reinforcement schedules, where the correct response is paired with a desirable consequence such as food. In contrast, a number of other learning processes that are used in training have been widely studied in other species, but have received little scientific investigation in the horse. These include: negative reinforcement, where performance of the correct response is followed by removal of, or decrease in, intensity of a unpleasant stimulus; punishment, where an incorrect response is paired with an undesirable consequence, but without consistent prior warning; secondary conditioning, where a natural primary reinforcer such as food is closely associated with an arbitrary secondary reinforcer such as vocal praise; and variable or partial conditioning, where once the correct response has been learnt, reinforcement is presented according to an intermittent schedule to increase resistance to extinction outside of training.

Animals↗
PubMed1995

Pigeons' preference for variable-interval water reinforcement under widely varied water budgets.

Water budget of pigeons was varied to assess the dependence of risk-sensitive preferences upon economic context such as has been reported for energy-budget manipulations with small animals in behavioral ecology research. Fixed- and variable-interval terminal-link water schedules reinforced choice between equal variable-interval initial-link schedules arranged on two pecking keys. While keeping a severely restrictive budget the same across three phases of the experiment, a contrasting distinct ample budget was arranged in each. To mimic typical methods in behavioral ecology studies, in each ample budget a more than three-fold increase in amount of water per reinforcer presentation was instituted simultaneously with significantly increased overall access to water. Total choice response rates plummeted in the ample budgets, and body weights either increased significantly or remained unchanged in different phases as expected by the nature of the different manipulations. Clear preferences for the variable-interval schedule were found throughout the experiment, except for rare instances of key bias. The results agree with similar operant food-reinforcement studies and extend conditions under which risk preference apparently does not depend upon economic context.

Animals↗
PubMed1993

Persistence of ethanol self-administration as a function of interreinforcer interval and concentration.

Dipper cups filled with an ethanol solution were presented to Long-Evans hooded rats according to multiple extinction x s fixed-ratio 1 (mult EXT x s FR1) schedules of reinforcement. The scheduled duration of the EXT component was varied to manipulate minimum interreinforcer interval. Increasing the minimum interreinforcer interval by increasing the EXT component was used to challenge responding maintained by ethanol for purposes of evaluating the persistence of ethanol-maintained responding. EXT durations of 0 s (baseline conditions of continuous reinforcement) to 480 s were examined across ethanol concentrations of 0 (water, vehicle), 2, 4, 8, 16, and 32% (w/v). Increasing the EXT component duration resulted in reductions in the number of dipper presentations obtained at each concentration. Reductions in dipper presentations were less, relative to 0-s baseline conditions, the higher the concentration of the ethanol solution available. It was concluded that increasing the ethanol concentration that is self-administered increases the strength of responding that is subsequently maintained in that drug-maintained behavior becomes more resistant to modulation by a procedure (scheduling minimum interreinforcer intervals) which generally reduces numbers of drug deliveries.

Alcohol Drinking↗
PubMed1967

Behavioral contrast and relative reinforcement frequency in two multiple schedules.

After preliminary variable-interval training, one group of pigeons was trained on a series of multiple variable-interval low-rate reinforcement schedules, while another group was trained on a series of multiple variable-interval fixed-ratio reinforcement schedules. Contrast effects were observed as variable-interval baseline rate changed in a direction away from the change in reinforcement frequency in the other component. The effects of the variable-interval component on performance in the low-rate and fixed-ratio reinforcement components in the multiple schedules were assessed by comparing the birds' performances on each of these schedules alone. Fixed-ratio reinforcement schedules showed a susceptibility to contrast effects, low-rate reinforcement schedules did not. The rate of reinforcement in fixed-ratio schedules at which no interaction occurred in the multiple schedules was higher than that in variable-interval 1-min schedules, suggesting that pigeons may prefer time-based, rather than response-based, reinforcement.

Animals↗
PubMed1981

The role of discriminative stimuli in concurrent performances.

Key pecking in pigeons was examined under concurrent and parallel arrangements of two independent and simultaneously available variable-interval schedules. Pecks on the changeover key alternated the schedule of reinforcement for responses on the main key. Under concurrent schedules, discriminative stimuli were paired with the reinforcement schedule arranged in each component and changeover responses also alternated these stimuli. Under parallel schedules, changeover responses alternated the effective reinforcement schedule, but did not change the discriminative stimulus. On concurrent procedures, changeover response rate was inversely related to the difference in reinforcement rate between the two components, whereas on parallel schedules no consistent relationship was found. With both schedules, absolute response and reinforcement rates were positively related, although for a given set of reinforcement frequencies, rates were often higher on the concurrent schedules. On concurrent schedules, relative response rates and relative times were equal to relative reinforcement rates. On parallel schedules these ratios were positively related, but response and time ratios were much smaller than were obtained with comparable concurrent schedules. This inequality was most pronounced when absolute reinforcement frequencies were lowest.

Journal Article↗
PubMed2003

MPR.

Mathematical Principles of Reinforcement (MPR) is a theory of reinforcement schedules. This paper reviews the origin of the principles constituting MPR: arousal, association and constraint. Incentives invigorate responses, in particular those preceding and predicting the incentive. The process that generates an associative bond between stimuli, responses and incentives is called coupling. The combination of arousal and coupling constitutes reinforcement. Models of coupling play a central role in the evolution of the theory. The time required to respond constrains the maximum response rates, and generates a hyperbolic relation between rate of responding and rate of reinforcement. Models of control by ratio schedules are developed to illustrate the interaction of the principles. Correlations among parameters are incorporated into the structure of the models, and assumptions that were made in the original theory are refined in light of current data.

Journal Article↗
PubMed2005

The anxiogenic drug yohimbine reinstates palatable food seeking in a rat relapse model: a role of CRF1 receptors.

The major problem in treating excessive eating is high rates of relapse to maladaptive eating habits during diet treatments; this relapse is often induced by stress or anxiety states. Preclinical studies have not explored this clinical problem. Here, we adapted a reinstatement model (commonly used to study relapse to abused drugs) to examine the role of stress and anxiety in relapse to palatable food seeking during dieting. Rats were placed on restricted diet (75-80% of daily standard food) and for 12 intermittent training days (9 h/day, every other day) lever-pressed for palatable food pellets (25% fat, 48% carbohydrate) under a fixed ratio 1 (20-s timeout) reinforcement schedule. Subsequently, the rats were given 10 daily extinction sessions during which lever presses were not reinforced, and were then injected with yohimbine (an alpha-2 adrenoceptor antagonist that induces stress and anxiety in humans and non-humans) or given a single food pellet to assess reinstatement of food seeking. The rats rapidly learned to lever press for the palatable pellets and across the training days the ratio of timeout nonreinforced lever presses to reinforced lever presses progressively increased more than three-fold, suggesting the development of compulsive eating behavior. After extinction, yohimbine injections and pellet priming reliably reinstated food seeking. The corticotropin-releasing factor1 (CRF1) receptor antagonist antalarmin attenuated the reinstatement induced by yohimbine, but not pellet priming. Antalarmin also reversed yohimbine's anxiogenic effects in the social interaction test. These data suggest that CRF is involved in stress-induced relapse to palatable food seeking, and that CRF1 antagonists should be considered for the treatment of maladaptive eating habits.

Adrenergic alpha-Antagonists↗
PubMed1991

Time-, schedule-, and reinforcer-dependent effects of pimozide and amphetamine.

Rats performed on two multiple random-interval schedules, in which sequences of ascending or descending reinforcement densities were balanced between the schedules and between the two halves of the session. Using a standard reinforcer (10% sucrose pellets), pimozide decreased response rates, while amphetamine increased responding. The effects of both drugs were schedule dependent: larger changes were evident in low response rate, reinforcement-lean components than in high response rate, reinforcement-rich components. Both effects were also time dependent, increasing over the course of the session; this casts serious doubt on the applicability of Herrnstein's matching law for studying agents acting on brain dopamine. Increasing the period of food deprivation increased response rates, while withdrawing food deprivation decreased responding. These effects were also schedule dependent, but were time dependent. Substituting 95% sucrose pellets for standard 10% sucrose pellets caused an immediate and sustained decrease in responding, and up to 10% of earned reinforcement was not consumed. Pimozide increased response rates within reinforcement-lean components and reinstated the complete consumption of earned reward typical of standard reinforcement. These apparently paradoxical effects may be consistent with a decrease in the rewarding properties of sucrose pellets. Despite low response rates, amphetamine did not affect responding maintained by 95% sucrose pellets but did further reduce the consumption of earned reward. These results call into question the generality of the rate-dependency principle in the action of psychomotor stimulants.

Amphetamine↗
PubMed1976

Aftereffects of reinforcement on variable-ratio schedules.

On each of variable-ratio 10, 40, and 80 schedules of reinforcement, when rats' lever-pressing rates were stable, the concentration of a liquid reinforcer was varied within sessions. The duration of the postreinforcement pause was an increasing function of the reinforcer concentration, this effect being more marked the higher the schedule parameter. The running rate, calculated by excluding the postreinforcement pause, was unaffected by concentration. The duration of the postreinforcement pause increased with the schedule parameter, but the proportion of the interreinforcement interval taken up by the pause decreased. Consequently, the overall response rate was an increasing function of the schedule parameter; i.e., it was inversely related to reinforcement frequency, contrary to the law of effect. The running rate, however, decreased with the reinforcement frequency, in accord with the law of effect. When 50% of reinforcements were randomly omitted, the postomission pause was shorter than the postreinforcement pause, but the running rate of responses was not affected.

Journal Article↗
PubMed1987

Treatment of pica in an adult disabled by autism by differential reinforcement of incompatible behavior.

The usefulness of differential reinforcement of incompatible behavior was examined in the treatment of pica in a young man severely disabled by autism in a nonsheltered place of employment. The results indicated that a reduction in pica could be achieved by differential reinforcement of other behavior (DRO). Behaviors which were reinforced included remaining in this assigned location, keeping his hands on his work, working quickly and keeping his mouth clear. Reinforcements included favorite drinks, snacks, activities and praise. Treatment procedures were implemented by direct care paraprofessional staff. Withdrawal of treatment resulted in an increase in pica, with renewed reduction on reinstatement of the reinforcement schedule.

Adult↗
PubMed2006

Role of food type in yohimbine- and pellet-priming-induced reinstatement of food seeking.

We have recently adapted a reinstatement model, commonly used to study relapse to drugs of abuse, to study the role of stress and anxiety in relapse to palatable food seeking [Ghitza UE, Gray SM, Epstein DH, Rice KC, Shaham Y. The anxiogenic drug yohimbine reinstates palatable food seeking in a rat relapse model: a role of CRF(1) receptors. Neuropsychopharmacology [in press]]. We found that the anxiogenic drug yohimbine, as well as pellet-priming, reinstate food seeking in food restricted rats previously trained to lever press for palatable food pellets (25% fat, 48% carbohydrate). Here, we studied the generality of the effect of yohimbine and pellet priming on reinstatement of food seeking by using three distinct pellet types: non-sucrose carbohydrate (NSC) (5.5% fat, 60% carbohydrate, 4.5% fiber), fiber (0% fat, 0% carbohydrate, 91% fiber) and sucrose (0% fat, 91% carbohydrate, 4% fiber). Rats were placed on a restricted diet (75-80% of daily standard food) and for 9-12 intermittent training days (9 h/day, every other day) lever-pressed for the food pellets under a fixed ratio-1 (20-s timeout) reinforcement schedule. Subsequently, the rats were given 9-10 daily extinction sessions during which lever-presses were not reinforced, and were then injected with yohimbine (0, 0.5, 1.0, 2.0 mg/kg, i.p.) or given a single food pellet to induce reinstatement of food seeking. Yohimbine reinstated food seeking previously reinforced by NSC and sucrose pellets, but had a minimal effect on food seeking in rats previously trained to lever press for fiber pellets. Pellet priming produced a greater degree of reinstatement of lever pressing in rats previously trained on NSC pellets than in rats trained on fiber or sucrose pellets. Results suggest that the magnitude of the effect of yohimbine and pellet priming on reinstatement of food seeking depends in part on the composition of the food pellets used during training.

Animals↗
PubMed1977

Studies of operant and reflexive key pecks in the pigeon.

The duration of pigeons' key pecks was studied in three experiments. Experiment I revealed that key pecks early in exposure to continuous reinforcement were of short duration, as were key pecks observed on an omission procedure in which pecks prevented food delivery. Key pecks later in exposure to continuous reinforcement, and those that occurred on positive automaintenance procedures, were of long duration. In Experiment II, pigeons were exposed to fixed-interval and fixed-ratio reinforcement schedules, and durations were recorded separately for each quarter of each interval or ratio. On fixed interval, durations were shorter in the first quarter of each interval than in subsequent quarters; on fixed ratio, durations were longer in the first quarter of the ratio than in subsequent quarters. These data parallel observations of concurrent operant responding and salivation in dogs. In Experiment III, pigeons were exposed to a discrete trial, differential-reinforcement-of-low-rate 6-sec schedule. Durations of responses in the first 2 sec of the trial were substantially shorter than those of responses that occurred later. The data from all three experiments support the view that the pigeon's "key peck" actually consists of two subclasses of peck, one reflexive and one operant.

Journal Article↗
PubMed2003

Extending mathematical principles of reinforcement into the domain of behavioral pharmacology.

Mathematical principles of reinforcement (MPR) attempts to integrate the empirical laws of reinforcement schedules that have accumulated over the decades. MPR is based on three principles: incentives excite behavior; there are temporal constraints on responding; and coupling of responses to reinforcers strengthens behavior [Behav. Brain Sci. 17 (1994) 105]. In the present paper MPR is extended into the domain of behavioral pharmacology, specifically to model the effects of D-amphetamine on operant behavior. In Experiment 1a, a five-component multiple fixed-ratio schedule was designed to generate behavioral baselines that were subsequently used to assess drug effect. In Experiments 1b and 1c, the quality and quantity of reinforcer were manipulated. The data generated by the three experiments were consistent with MPR. In Experiment 2, MPR was used to model the effects of D-amphetamine on rats responding under the five-component multiple fixed-ratio schedule. According to the model, the rate-decreasing effects of D-amphetamine were due primarily to motor disruption and secondarily to increased impulsivity; at the highest dosages, D-amphetamine also may have decreased the incentive value of food.

Journal Article↗
PubMed1994

Ethanol as a reinforcer: a review of laboratory studies of non-human primates.

This article reviews studies of ethanol self-administration in non-human primates. Between approximately 1960 and 1980 research programs at three university medical centers (Michigan, Minnesota and Baylor) established that ethanol could function as a reinforcer when delivered either intravenously, intragastrically or orally. Variables such as session length, dose and intermittent reinforcement schedules were examined, and tolerance and physiological dependence on ethanol were also studied. Procedures used to establish abused drugs as reinforcers via the intravenous, intragastric and oral route are also effective in the particular case of ethanol. Under conditions of limited access (e.g. 3h per day), the variables that control behavior reinforced by ethanol are the same as those that govern behavior reinforced by other drugs. Moreover, the functional relations between these variables and ethanol-reinforced responding are similar to the functional relations between the same variables and other drug reinforcers. However, with continuous 24h access to ethanol, differences appear with respect to other sedative-hypnotic drugs. In contrast to these other drugs, intravenous ethanol use results in a suppression of food intake, weight loss, self-initiated abstinence, and often, death. When intravenous and oral ethanol self-administration are compared, two important differences emerge: the maximum intakes via the intravenous route exceed the maximum intakes via the oral route, and, perhaps surprisingly, the doses required to maintain responding are lower with the oral route. Studies since 1980 have increased the scope of ethanol reinforcement research and also corroborated and extended earlier findings. In summary, ethanol can function as an effective reinforcer for non-human primates.

Journal Article↗
PubMed1994

A behavioural training programme for chronic schizophrenic patients. A three-month randomised controlled trial in Beijing.

This paper discusses the effectiveness of an in-patient rehabilitation programme administered by nurses that combines life skills training, active encouragement, and a token economy. Fifty-two chronic schizophrenic patients with prominent negative symptoms who had been continuously in hospital for at least a year were randomly assigned to the experimental or control group. The training and associated reinforcement schedule were administered daily to experimental subjects by two specially trained rehabilitation nurses. Control subjects did not receive training or reinforcement but were individually asked to perform the same daily tasks and participate in the same activities as the experimental-group subjects. Patients in both groups received their previous dosage of medication throughout the trial. After three months the severity of negative symptoms, as assessed by blind evaluators, decreased in both groups of subjects, but the improvement in the experimental group was much greater than that in the control group. These findings demonstrate the efficacy of behavioural interventions for chronic schizophrenic in-patients in China and highlight the importance of changing the role of Chinese psychiatric nurses from that of custodians who control patients' behaviour to that of therapists who provide psychological and behavioural treatment.

Activities of Daily Living↗
PubMed1998

Comparison of the alcohol-preferring P rat to the Wistar rat in behavioral tests of impulsivity and anxiety.

To determine whether the selectively bred alcohol preferring P rat displays impulsive and anxiety-related behaviors, as have been noted in Type 2 human alcoholics, P rats were compared with outbred Wistar rats, the strain from which P rats were derived, on a series of behaviors reflecting impulsivity and anxiety. The two groups were also compared on their volitional consumption of ethanol. When compared with the Wistar rats, the P rats preferred a higher concentration of ethanol and imbibed a much greater amount of ethanol when they were offered their preferred concentration. However, the behavioral tasks produced inconsistent results. The P rats completed 100 bar presses for food in less time when tested on a constant reinforcement schedule, which suggests that they are hyperactive compared to Wistar rats. However, the P rats also emitted a higher percentage of reinforced responses on differential reinforcement of low rate responding (DRL)-10s and gnawed less from a cork stopper, which suggests that they are less impulsive and possibly neophobic. The two groups did not differ on emergence into or activity in an open field, their activity in or open-arm duration in the elevated plus maze, or performance on DRL-5s and DRL-15s. Collectively, the behavioral data suggest that P rat does not serve as a model for the anxiety and impulsiveness associated with the Type 2 alcoholic individual.

Alcohol Drinking↗