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PubMed1976

A comparison of the key-peck and treadle-press operants in the pigeon: differential-reinforcement-of-low-rate schedule of reinforcement.

Key pecking and treadle pressing in pigeons were compared under concurrent (key-treadle) and single-operant differential-reinforcement-of-low-rate schedules of food reinforcement ranging from 5 to 60 sec (concurrent procedure) or 5 to 120 sec (single-operant procedure). Under both procedures, the two operants followed the same general law: decreasing response rate and reinforcement rate and increasing number of responses per reinforcement as a function of increasing schedule interval. High correlations were found between key pecking and treadle pressing for the measures of response rate, reinforcement rate, and responses per reinforcement. Regression equations allowed the prediction of treadle pressing from key pecking. More bursting occurred in responding to the key, and key pecking showed a more precise temporal discrimination than treadle pressing. A test for sequential dependencies between key and treadle responses showed significant dependencies not only under the concurrent procedure but also in data created artificially by merging key and treadle sequences from different pigeons under the concurrent procedure and from the same pigeon under the single-operant procedure. It seems likely that the sequential dependencies found were due to the independent action of the schedule on each operant and that behavioral dependencies did not occur with the concurrent training procedure. The key-peck operant does not appear to have any special qualities that preclude its use in discovering general laws of behavior, at least under the differential-reinforcement-of-low-rate schedule. The usefulness of the key peck in other situations requires direct experimental study.

Journal Article↗

PubMed2006

Fracture resistance of inlay-retained fixed partial dentures reinforced with fiber-reinforced composite.

In this study, the effect on the fracture load of inlay-retained composite fixed partial dentures (FPDs) caused by reinforcing them with fiber-reinforced composite (FRC) in different positions was examined. Experimental FPDs were fabricated using Estenia/EG Fiber (Kuraray Medical). Pontic reinforcement was then performed in one of the following three ways: reinforced the central area in a single line or in double straight lines, or reinforced the bottom in a curved line. The finding was that, when the area ranging from the connector to the bottom of the pontic was reinforced with FRC in a curved line, the fracture load of the FPDs tended to become higher. In addition, the FPDs fractured mainly at the veneering composite of the connector area. Based on the results of this study, it was concluded that reinforcement using FRC is effective, and that the veneering composite in the connector area needs to have sufficient strength to prevent the fractures.

Acrylic Resins↗

PubMed1988

The effects of haloperidol on the partial reinforcement extinction effect (PREE): implications for neuroleptic drug action on reinforcement and nonreinforcement.

The effects of haloperidol 0.1 mg/kg on the partial reinforcement extinction effect (PREE) paradigm at one trial a day, were examined. Two groups of rats were trained to run in a straight alley. The continuously reinforced (CRF) group received food reward on every trial. The partially reinforced (PRF) group was rewarded on a quasi-random 50% schedule. All animals were then tested in extinction. Haloperidol 0.1 mg/kg was administered in a 2 x 2 design, i.e., drug-no drug in acquisition and drug-no drug in extinction. The PREE, i.e., increased resistance to extinction of partially reinforced as compared to continuously reinforced animals, was obtained in all four drug conditions. The administration of haloperidol in acquisition increased markedly resistance to extinction in CRF animals. The administration of the drug in extinction decreased resistance to extinction in both CRF and PRF animals. The results are explained in terms of two independent actions of haloperidol: the well-known effect of reduction in the effectiveness of reinforcement as well as enhancement of the effectiveness of nonreinforcement.

Animals↗

PubMed2002

Reinforcement magnitude and responding during treatment with differential reinforcement.

Basic findings indicate that the amount or magnitude of reinforcement can influence free-operant responding prior to and during extinction. In this study, the relation between reinforcement magnitude and adaptive behavior was evaluated with 3 children as part of treatment with differential reinforcement. In the first experiment, a communicative response was shaped and maintained by the same reinforcer that was found to maintain problem behavior. Two reinforcement magnitudes (20-s or 60-s access to toys or escape from demands) were compared and found to be associated with similar levels of resistance to extinction. The relation between reinforcement magnitude and response maintenance was further evaluated in the second experiment by exposing the communicative response to 20-s or 300-s access to toys or escape. Results for 2 participants suggested that this factor may alter the duration of postreinforcement pauses.

Adult↗

PubMed1968

Secondary reinforcement and number of primary reinforcements.

Pigeons' pecks on either of two concurrently available response keys produced secondary reinforcers according to independent one-minute variable-interval schedules. Different secondary reinforcers, in the presence of which the rates of primary reinforcement were equal, were associated with each key. The rate of pecking maintained by each secondary reinforcer varied directly, but nonproportionally, with the number of primary reinforcements given in the presence of the secondary reinforcer.

Animals↗

PubMed1994

Effects of social context, reinforcer probability, and reinforcer magnitude on humans' choices to compete or not to compete.

In the first two experiments, subjects' choices to earn points (exchangeable for money) either by competing with a fictitious opponent or by not competing were studied. Buskist, Barry, Morgan, and Rossi's (1984) competitive fixed-interval schedule was modified to include a second response option, a noncompetitive fixed-interval schedule. After choosing to enter either option, the opportunity for reinforcers became available after the fixed-interval's duration had elapsed. Under the no-competition condition, points were always available after the interval had elapsed. Under the competition condition, points were available based on a predetermined probability of delivery. Experiments 1 and 2 examined how reinforcer probabilities and reinforcer magnitudes affected subjects' choices to compete. Several general conclusions can be made about the results: (a) Strong preferences to compete were observed at high and moderate reinforcer probabilities; (b) competing was observed even at very low reinforcer probabilities; (c) response rates were always higher in the competition component than in the no-competition component; and (d) response rates and choices to compete were insensitive to reinforcer-magnitude manipulations. In Experiment 3, the social context of this choice schedule was removed to determine whether the high levels of competing observed in the first two experiments were due to a response preference engendered by the social context provided by the experimenters through instructions. In contrast to the first two experiments, these subjects preferred the 60-s fixed-interval schedule (formerly the no-competition option), indicating that the instructions themselves were responsible for the preference to compete. This choice paradigm may be useful to future researchers interested in the effects of other independent variables (e.g., drugs, social context, instructions) on competitive behavior.

Adult↗

PubMed1986

Effects of variations of reinforcement magnitude on alcohol discrimination using intracranial stimulation as the reinforcer.

Male Wistar rats were trained to discriminate intraperitoneal injections of 2 g/kg of alcohol from 0.5 g/kg alcohol injections. Intracranial stimulation in the posterolateral area of the hypothalamus served as the reinforcer according to a FR 10 schedule of bar pressing. After discrimination between the two alcohol doses had been established, the response-reinforcement contingency was modified by progressively increasing the intensity of the intracranial stimulation. The results indicate that the generalization gradient varies with the number of reinforcements. The more the lever associated with a training dose was reinforced, the more the ED50 had the tendency to approach this dose. Our paradigm, by using electrical brain reinforcer, allowed to deliver in an equal manner the reinforcement schedule in order to obtain equal performances and equal number of reward received.

Animals↗

PubMed2004

Simulation of rat behavior by a reinforcement learning algorithm in consideration of appearance probabilities of reinforcement signals.

Brown and Wanger [Brown, R.T., Wanger, A.R., 1964. Resistance to punishment and extinction following training with shock or nonreinforcement. J. Exp. Psychol. 68, 503-507] investigated rat behaviors with the following features: (1) rats were exposed to reward and punishment at the same time, (2) environment changed and rats relearned, and (3) rats were stochastically exposed to reward and punishment. The results are that exposure to nonreinforcement produces resistance to the decremental effects of behavior after stochastic reward schedule and that exposure to both punishment and reinforcement produces resistance to the decremental effects of behavior after stochastic punishment schedule. This paper aims to simulate the rat behaviors by a reinforcement learning algorithm in consideration of appearance probabilities of reinforcement signals. The former algorithms of reinforcement learning were unable to simulate the behavior of the feature (3). We improve the former reinforcement learning algorithms by controlling learning parameters in consideration of the acquisition probabilities of reinforcement signals. The proposed algorithm qualitatively simulates the result of the animal experiment of Brown and Wanger.

Algorithms↗

PubMed2002

Comparison of the reinforcing efficacy of two dopamine D2-like receptor agonists in rhesus monkeys using a progressive-ratio schedule of reinforcement.

High-efficacy D2-like dopamine (DA) receptor agonists can function as positive reinforcers when made available to animals for intravenous self-administration under a fixed-ratio (FR) schedule of reinforcement. In a previous study, however, low-efficacy D2-like agonists failed to maintain self-administration under an FR schedule, suggesting that agonist efficacy is directly related to efficacy as a positive reinforcer. To examine this hypothesis further, the present study compared two D2-like DA receptor agonists that maintained FR responding, but differ in their D2-like receptor efficacy and selectivity, using a procedure designed to rank-order drugs according to their efficacy as reinforcers. Rhesus monkeys (n=5) were prepared with chronic, indwelling intravenous catheters and allowed to self-administer cocaine (0.1 mg/kg/injection) or saline on different days under a progressive-ratio (PR) schedule. When responding was stable, doses of the full D2-like agonist R(-)-propylnorapomorphine (NPA) or the partial D2-like agonist R(-)-apomorphine (APO) were made available for self-administration in the test sessions. Both compounds maintained self-administration with sigmoidal or biphasic dose-response functions. Surprisingly, the lower efficacy agonist APO was the more efficacious positive reinforcer. This result fails to support the hypothesis that D2-like receptor efficacy is directly related to efficacy as a reinforcer. It is possible that other pharmacological effects, e.g., D1 receptor activity, influenced self-administration.

Animals↗

PubMed1980

Reinforcement and the organization of behavior in golden hamsters: brain stimulation reinforcement for seven action patterns.

Golden hamsters were reinforced with intracranial electrical stimulation of the lateral hypothalamus (ICS) for spending time engaging in one of seven topographically defined action patterns (APs). The stimulation used as reinforcer elicited hoarding and/or feeding and supported high rates of bar pressing. In Experiment 1, hamsters were reinforced successively for digging, open rearing, and face washing. Digging increased most in time spent, and face washing increased least. Experiments 2-5 examined these effects further and also showed that "scrabbling," like digging, was performed a large proportion of the time, almost without interruption, for contingent ICS but that scratching the body with a hindleg and scent-marking showed relatively little effect of contingent ICS, the latter even in an environment that facilitated marking. In Experiment 6, naive hamsters received ICS not contingent on behavior every 30 sec (fixed-time 30-sec schedule). Terminal behaviors that developed on this schedule were APs that were easy to reinforce in the other experiments, but a facultative behavior, face washing, was one not so readily reinforced. Experiment 7 confirmed a novel prediction from Experiment 6--that wall rearing, a terminal AP, would be performed at a high level for contingent ICS. All together, the results point to both motivational factors and associative factors being involved in the considerable differences in performance among different reinforced activities.

Animals↗

PubMed1995

Sucrose, ethanol, and sucrose/ethanol reinforced responding under variable-interval schedules of reinforcement.

Adding sweeteners to ethanol solutions is a common method of inducing rats to consume ethanol. However, it has usually been assumed that it is the sweet taste and/or the calories contained in the sweet solution that controls consumption. The present experiment examined the role of ethanol in controlling responding reinforced by ethanol or an ethanol/sucrose mixture compared with sucrose solutions of various concentrations. After initiation to self-administer 10% (v/v) ethanol using the sucrose-substitution method, rats were trained to respond under a concurrent VI 5" VI 5" schedule. During one condition, responding on one lever was reinforced by the presentation of 10% ethanol, and responding on a second lever was reinforced by water or one of the following sucrose solutions: 1% (w/v), 1.5%, 2%, 2.5%, 3%, and 5%. During a subsequent condition, responding reinforced by a 10% ethanol/2% sucrose mixture was compared under the concurrent schedule with responding reinforced by water, 2%, 2.5%, 3%, 5%, or 10% sucrose (w/v). The results indicated that the ethanol or ethanol/sucrose mixture maintained more responding than did sucrose solutions that were sweeter. Data support the conclusion that, after initiation, the taste and/or pharmacological effects of ethanol had become an important component of the reinforcing stimulus independent of the sweetener.

Alcohol Drinking↗

PubMed1994

Effects of reinforcement history on responding under progressive-ratio schedules of reinforcement.

The effects of experimental history on responding under a progressive-ratio schedule of reinforcement were examined. Sixteen pigeons were divided into four equal groups. Groups 1 to 3 were trained to peck a key for food under a fixed-ratio, variable-ratio, or differential-reinforcement-of-low-rate schedule of reinforcement. After training, these pigeons were shifted to a progressive-ratio schedule, later were shifted back to their original schedule (with decreased rates of reinforcement), and finally were returned to the progressive-ratio schedule. Pigeons in Group 4 (control) were maintained on the progressive-ratio schedule for the entire experiment. To test for potential "latent history" effects, pigeons responding under the progressive-ratio schedule were injected with d-amphetamine and given behavioral-momentum tests of prefeeding and extinction. Experimental histories affected responding in the immediate transition to the progressive-ratio schedule; response rates of pigeons with variable-ratio and fixed-ratio histories were higher than rates of pigeons with differential-reinforcement-of-low-rate and progressive-ratio-only histories. Pigeons with differential-reinforcement-of-low-rate histories, and to a lesser degree pigeons with variable-ratio and fixed-ratio histories, also had shorter postreinforcement pauses than pigeons with only a progressive-ratio history. No consistent long-term effects of prior contingencies on responding under the progressive-ratio schedule were evident. d-Amphetamine and resistance-to-change tests failed to reveal consistent latent history effects. The data suggest that history effects are sometimes transitory and not susceptible to latent influences.

Animals↗

PubMed2003

Responding for sucrose and wheel-running reinforcement: effects of sucrose concentration and wheel-running reinforcer duration.

Six male albino rats were placed in running wheels and exposed to a fixed-interval 30-s schedule of lever pressing that produced either a drop of sucrose solution or the opportunity to run for a fixed duration as reinforcers. Each reinforcer type was signaled by a different stimulus. In Experiment 1, the duration of running was held constant at 15 s while the concentration of sucrose solution was varied across values of 0, 2.5. 5, 10, and 15%. As concentration decreased, postreinforcement pause duration increased and local rates decreased in the presence of the stimulus signaling sucrose. Consequently, the difference between responding in the presence of stimuli signaling wheel-running and sucrose reinforcers diminished, and at 2.5%, response functions for the two reinforcers were similar. In Experiment 2, the concentration of sucrose solution was held constant at 15% while the duration of the opportunity to run was first varied across values of 15, 45, and 90 s then subsequently across values of 5, 10, and 15 s. As run duration increased, postreinforcement pause duration in the presence of the wheel-running stimulus increased and local rates increased then decreased. In summary, inhibitory aftereffects of previous reinforcers occurred when both sucrose concentration and run duration varied; changes in responding were attributable to changes in the excitatory value of the stimuli signaling the two reinforcers.

Animals↗

PubMed2006

Disruption of responding maintained by conditioned reinforcement: alterations in response-conditioned-reinforcer relations.

An observing procedure was used to investigate the effects of alterations in response-conditioned-reinforcer relations on observing. Pigeons responded to produce schedule-correlated stimuli paired with the availability of food or extinction. The contingency between observing responses and conditioned reinforcement was altered in three experiments. In Experiment 1, after a contingency was established in baseline between the observing response and conditioned reinforcement, it was removed and the schedule-correlated stimuli were presented independently of responding according to a variable-time schedule. The variable-time schedule was constructed such that the rate of stimulus presentations was yoked from baseline. The removal of the observing contingency reliably reduced rates of observing. In Experiment 2, resetting delays to conditioned reinforcement were imposed between observing responses and the schedule-correlated stimuli they produced. Delay values of 0, 0.5, 1, 5, and 10 s were examined. Rates of observing varied inversely as a function of delay value. In Experiment 3, signaled and unsignaled resetting delays between observing responses and schedule-correlated stimuli were compared. Baseline rates of observing were decreased less by signaled delays than by unsignaled delays. Disruptions in response-conditioned-reinforcer relations produce similar behavioral effects to those found with primary reinforcement.

Animals↗

PubMed1997

Excitotoxic lesions of the amygdala fail to produce impairment in visual learning for auditory secondary reinforcement but interfere with reinforcer devaluation effects in rhesus monkeys.

Aspiration lesions of the amygdala were found previously to produce a severe impairment in visual discrimination learning for auditory secondary reinforcement in rhesus monkeys (Gaffan and Harrison, 1987). To determine whether excitotoxic amygdala lesions would also produce this effect, we trained four naive rhesus monkeys on the same task. The monkeys were required to learn 40 new visual discrimination problems per session in a situation in which visual choices were guided by an auditory secondary reinforcer that had been previously associated with food reward. Bilateral excitotoxic lesions of the amygdala had no effect on the rate of learning visual discrimination problems for auditory secondary reinforcement. We also tested the amygdalectomized monkeys on a reinforcer devaluation task and compared their performance with a group of three normal monkeys. The monkeys first learned to discriminate 60 pairs of objects, baited with two different food rewards. Each of the food rewards was then devalued by selective satiation in two separate experimental sessions. Normal controls tended to avoid displacing objects that covered the devalued food to a significantly greater degree than did the amygdalectomized monkeys, indicating that the excitotoxic amygdala damage interfered with reinforcer devaluation effects. Our results are consistent with the idea that the amygdala is necessary for learning the association between stimuli and the value of particular food rewards; however, the amygdala is not necessary for maintaining the value of secondary reinforcers, once they have been learned.

Acoustic Stimulation↗

PubMed1984

Effects on preference of reinforcement delay, number of reinforcers, and terminal-link duration.

Three experiments used concurrent-chains procedures to examine the effects of reinforcement delay, number of reinforcers, and terminal-link duration on preference. In Condition 30 of Experiment 1, food was delivered after 30 seconds in each 150-second terminal link, with four additional food deliveries occurring at 30-second intervals in one of the links. In Condition 5, food was delivered after 5 seconds in each 25-second terminal link, and the four additional reinforcers were delivered at 5-second intervals. Preferences for the multiple-food chain were greater in Condition 30. In Experiment 2, the terminal link(s) providing only one reinforcer terminated immediately after delivery of the reinforcer. Preferences for the multiple-food chain were smaller than in Experiment 1. In Condition 5 of Experiment 3, food was delivered after 5, 75, 100, 125, and 150 seconds in one 150-second link and after 5 seconds in the other. Condition 50 differed only in that the first (or only) reinforcer in each link was delivered after 50 seconds instead of after 5 seconds. Preferences for the multiple-food chain were greater in Condition 50. Results of Experiments 1 and 2 do not correspond to results obtained by Moore (1979).

Journal Article↗

PubMed1995

Delayed matching-to-sample performance: Effects of relative reinforcer frequency and of signaled versus unsignaled reinforcer magnitudes.

Six pigeons were trained on a delayed red-green matching-to-sample task that arranged four delays within sessions. Matching responses intermittently produced either 1.5-s access to food or 4.5-s access to food, and nonmatching responses produced either 1.5-s or 4.5-s blackout. Two phases were conducted: a signaled phase in which the reinforcer magnitudes (small and large) were signaled by houselights (positioned either on the left or right of the chamber), and an unsignaled phase in which there was no correlation between reinforcer magnitude and houselight position. In both phases, the relative frequency with which red and green matching responses produced food was varied across five values. Both matching accuracy and the sensitivity of performance to the distribution of reinforcers for matching responses decreased with increasing delays in both phases. In addition, accuracy and reinforcer sensitivity were significantly lower on signaled small-reinforcer trials compared with accuracy and sensitivity values on signaled large-reinforcer trials and on both types of unsignaled trials. These results are discussed in the context of research on both nonhuman animal and human memory.

Journal Article↗

PubMed1964

SECONDARY REINFORCEMENT AND RATE OF PRIMARY REINFORCEMENT.

Four pigeons were trained to peck at either of two response-keys. Pecking at either key occasionally produced a secondary reinforcer. Then, in the presence of the secondary reinforcer, further pecking occasionally produced the primary reinforcer, food. The relative rate at which each pigeon pecked to obtain a secondary reinforcer equalled the relative rate of primary reinforcement in its presence.

Animals↗