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PubMed1968

Fixed and variable schedules of response-independent reinforcement.

After response-dependent reinforcement established key-pecking as the predominant response, pigeons received schedules in which reinforcements occurred without reference to responding. These response-independent schedules involved either a reinforcement every 5 min, or reinforcements at irregular intervals that averaged 5 min. The response-independent schedules generated characteristic patterns of responding. The fixed schedule produced positively accelerated responding between reinforcements, and the variable schedule produced either steady rates, erratic, or negatively accelerated patterns. The patterns developed independent of the distribution of responses existing when the schedule was first imposed. The rate of responding varied for the three birds, but, for all, response-independent schedules decreased the rates below the level maintained by response-dependent reinforcement. Although the rate of responding was affected primarily by the events contiguous with reinforcement, the pattern of responding appeared to be determined mainly by the presentation of reinforcements in relation to time.

Animals↗

PubMed1971

Effects of pairing stimuli with reinforcement on multiple schedule performance of children.

A nonsense word was paired with reinforcement to determine if pairing affected emission of a response that produced the word in the signalled absence of reinforcement. Children were trained on a multiple schedule that consisted of a reinforcement component, conditioned reinforcement component, and control component, each set of contingencies being signalled by a different colored light. In the primary reinforcement component, lever presses produced reinforcers which, in some phases, were paired with a word. In the other two components, lever presses were not reinforced and a button was made accessible. Button presses in the conditioned reinforcement component produced the word to be (or being) paired, e.g., "yafeh", while button presses in the control component produced another word, e.g., "grunch". Button pressing increased when one of the words was being paired and decreased when pairing was discontinued, but directly related rate changes occurred also in the control component. The order of components was shown to be a contributing variable.

Acoustic Stimulation↗

PubMed1984

Responding during reinforcement delay in a self-control paradigm.

Eight pigeons chose between a small, immediate reinforcer and a large, increasingly delayed reinforcer. Responding during the large-reinforcer delays was examined. During large-reinforcer delays, pecks on one key produced the small, immediate reinforcer; pecks on the other key had no effect. Thus, a pigeon could reverse its initial choice of the large, delayed reinforcer, or it could maintain its original choice. Pigeons that made a relatively high number of initial large-reinforcer choices tended to maintain these choices, and those pigeons that actually received a relatively high number of large reinforcers, tended to respond more frequently on the ineffective key during the delay periods. The findings suggest that some previous studies of self-control training in pigeons may have resulted in increased self-control partially due to a lack of opportunity for the pigeons to change their choices.

Animals↗

PubMed1996

Reinforcing value of food in obese and non-obese women.

Food is a powerful reinforcer, and individual differences in the reinforcing efficacy of food may provide a mechanism to explain the excess intake and positive energy balance responsible for obesity. The present study tested the hypothesis that eating palatable food would be more reinforcing than engaging in sedentary activities (e.g. playing computer games) for obese in comparison to non-obese non-dietary restrained female college students. Subjects could choose to eat food or engage in sedentary activities based on their responding in a computer-generated concurrent schedules task. The reinforcement schedule associated with earning access to sedentary activities was held at variable ratio 2 (VR2) while the food reinforcement schedule was set at VR2 in the first trial of the choice task and doubled across the four subsequent trials from VR4 to VR32. Choice and consumption results indicated that eating was significantly more reinforcing than engaging in sedentary activities for obese subjects than non-obese subjects. Hedonics for the activities and foods were not correlated with total food reinforcers earned and did not differ between the groups. These results confirm the hypothesis that eating food is more reinforcing than selected alternative activities to a greater extent for obese than for non-obese young women.

Adult↗

PubMed1986

Chlorpromazine and pimozide alter reinforcement efficacy and motor performance.

This study evaluated the effects of chlorpromazine and pimozide on reinforced responding. In each session, rats were exposed to a series of five variable-interval reinforcement schedules. The response requirement was a lever press, the reward was a small portion of water, and the reinforcement rate varied from about 20 to 660 reinforcers per hour. Response rate was a negatively accelerated function of reinforcement rate, and the relationship between the two variables was described by the equation for a rectangular hyperbola (the matching law). One parameter of the hyperbola is equivalent to the asymptotic response rate and the other parameter is equivalent to the rate of reinforcement that maintains a one-half asymptotic response rate. Chlorpromazine (0.75-3.0 mg/kg) and pimozide (0.1-0.4 mg/kg) dose-dependently decreased response rates. At low doses, the response rate decreases were, for the most part, restricted to the low reinforcement rate schedules. In contrast, the highest dose tested decreased response rates at both low and high reinforcement rates. The patterns of response rate decreases resulted in dose-dependent changes in the parameters of the matching law equation. The shifts in the matching law parameters were discussed in terms of the motoric and motivational interpretations of neuroleptic-induced response rate changes.

Animals↗

PubMed1993

Effect of lesions of the ascending 5-hydroxytryptaminergic pathways on choice between delayed reinforcers.

The possible involvement of the ascending 5-hydroxytryptaminergic (5HTergic) pathways in determining the effectiveness of delayed positive reinforcers was investigated using Mazur's (1984) adjusting-delay paradigm. Fourteen rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei; 12 rats received sham lesions. The rats made repeated choices in a two-lever operant conditioning chamber between a smaller reinforcer delivered after a 2-s delay and a larger reinforcer delivered after a variable delay, the length of which was determined by the subject's previous choices. When the two reinforcers consisted of one and two food pellets, the "indifference point" (the delay to the larger reinforcer that rendered the two reinforcers equally effective) was shorter in the lesioned group than in the control group. Increasing the sizes of the reinforcers to three and six pellets reduced the indifference point in both groups and abolished the between-group difference. The levels of 5HT and 5-hydroxyindoleacetic acid (5HIAA) in the parietal cortex, hippocampus, amygdala, nucleus accumbens and hypothalamus were greatly reduced in the lesioned group, but the levels of noradrenaline and dopamine were not significantly affected. The results are consistent with the suggestion that the 5HTergic pathways play a role in maintaining the effectiveness of delayed reinforcers.

5,7-Dihydroxytryptamine↗

PubMedDate not supplied

A systems process of reinforcement.

Functional systems theory was used to consider the process of reinforcement of the actions on the body of reinforcing factors, i.e., the results of behavior satisfying the body's original needs. The systems process of reinforcement includes reverse afferentation entering the CNS from receptors acted upon by various parameters of the desired results, and mechanisms for comparing reverse afferentation with the apparatus which accepts the results of the action and the corresponding emotional component. A tight interaction between reinforcement and the dominant motivation is generated on the basis of the hologram principle. Reinforcement forms an apparatus for predicting a desired result, i.e. a result-of-action acceptor. Reinforcement procedures significant changes in the activities of individual neurons in the various brain structures involved in dominant motivation, transforming their spike activity for a burst pattern to regular discharges; there are also molecular changes in neuron properties. After preliminary reinforcement, the corresponding motivation induces the ribosomal system of neurons to start synthesizing special effector molecules, which organize molecular engrams of the acceptor of the action's result. Sensory mechanisms of reinforcement are considered, with particular reference to the information role of emotions.

Animals↗

PubMed2002

Orally delivered alprazolam, diazepam, and triazolam as reinforcers in rhesus monkeys.

RATIONALE: Benzodiazepines are among the most frequently prescribed drugs and are usually taken by mouth. However, there have been few studies of oral self-administration of these drugs, and the results of IV self-administration studies indicate that benzodiazepines are modest reinforcers. OBJECTIVES: To determine if orally delivered alprazolam, diazepam, and triazolam could serve as reinforcers for rhesus monkeys, and to determine some of the conditions under which benzodiazepine reinforced behavior occurs. METHODS: Diazepam or midazolam was initially established as a reinforcer by a fading procedure whereby increasing concentrations were added to a 1 or 2% ethanol solution, and subsequently the ethanol concentration was decreased in steps to zero. Diazepam- and midazolam-reinforced responding persisted in the absence of ethanol. Triazolam and alprazolam served as reinforcers when substituted for diazepam or midazolam. RESULTS: Alprazolam, diazepam, and triazolam served as effective reinforcers across a wide range of concentrations and under fixed-ratio sizes of 16 and 32. Rates of responding were usually far higher than that for the concurrently available vehicle, water. Drug intake (mg drug/kg body weight) generally increased with increases in drug concentration. When large drug amounts were consumed, signs of intoxication were observed. CONCLUSIONS: In contrast to reports of low response rates and weakly maintained behavior, the present results show that the three benzodiazepines can serve as effective reinforcers.

Administration, Oral↗

PubMed2003

Nicotine enhances responding with conditioned reinforcement.

RATIONALE: The mesolimbic dopamine system has been implicated in the primary reinforcing properties of drugs of abuse as well as in enhanced responding with conditioned reinforcement produced by psychomotor stimulant drugs. Despite clinical observations that nicotine self-administration (i.e. smoking) depends strongly upon conditioned reinforcement (i.e. cues support smoking behavior), little is known about whether nicotine directly affects motivational processes. OBJECTIVE: In these experiments, we investigated whether acute nicotine would influence responding with conditioned reinforcement and the degree to which pretreatment with the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine would modify any nicotine-induced behavioral effects. METHODS: After subjects had been trained to associate an initially neutral stimulus with water reward, they received acute nicotine (43,25-350 micro g/kg SC; -5 min) or saline injections and were tested on the acquisition of a new response for conditioned reinforcement paradigm. In separate experiments, the effect of pretreatment with the nicotinic acetylcholine receptor antagonist mecamylamine (300 or 1000 micro g/kg SC; -20 min) alone, or in combination with nicotine (350 micro g/kg SC; -5 min), on conditioned reinforcement was also examined. RESULTS: Acute nicotine injection produced a selective enhancement of responding with conditioned reinforcement (i.e. on the CR lever), without producing non-selective increases in overall responding. The effect of nicotine (350 micro g/kg SC; -5 min) was selectively blocked by mecamylamine (300 micro g/kg). CONCLUSIONS: These findings demonstrate that acute exposure to nicotine augments the control over behavior by a conditioned reinforcer, suggesting that nicotine may enhance motivational processes.

Animals↗

PubMed1981

Pimozide attenuates lever pressing for water reinforcement in rats.

Rats were trained to lever-press for water on a schedule of continuous reinforcement, then tested every fourth session on five occasions either under conditions of non-reinforcement or following injections of the dopamine receptor blocker pimozide (0.5 or 1.0 mg/kg) or the injection vehicle. The low dose of pimozide did not significantly attenuate responding until the fifth session. The high dose attenuated responding on all occasions, with residual responding decreasing progressively across repeated drug sessions. Responding in the pimozide conditions was never less than that of the non-reinforced control group. Responding in each condition was strongest in the early minutes of a session. After five sessions, rats were switched from the pimozide condition to the non-reinforced condition (or vice-versa) for one additional test day. Decreased responding continued for rats transferred from non-reinforcement to pimozide though not for rats transferred from pimozide to non-reinforcement. These data suggest a role for brain dopamine in behavior; they reflect the same patterns as have been seen with food reinforcement and with several centrally-acting reinforcers.

Animals↗

PubMed1990

Measuring threshold of reinforcing brain stimulation by the method of constant stimuli.

A new method for measuring threshold of reinforcing electrical brain stimulation is described and results of a parametric study using this method are presented. Two groups of rats were trained under a concurrent FR-CRF (fixed ratio-continuous reinforcement) schedule of reinforcement provided by electrical stimulation of the lateral hypothalamus. The invariant intermittent FR schedule of reinforcement was used to maintain a baseline of behavior while a superimposed concurrent CRF schedule was used to measure reinforcement magnitude by varying the intensity of the CRF stimulus between zero and a maximum. Increasing and decreasing stimulus intensity on the CRF schedule leads to a gradual disappearance, respectively reappearance, of post-reinforcement pauses (PRPs) on the concurrent FR schedule, providing a criterion for changeover in schedule control, and thus, for threshold of reinforcement. To illustrate the measurement of threshold according to psychophysical requirements of the Method of Constant Stimuli, different CRF intensities were given in a randomized order. In one group of animals FR and CRF stimuli were given through the same electrode. Another group received FR and CRF stimuli through separate electrodes implanted in different hemispheres of the brain. For both groups the duration of the PRP was used as the dependent variable. The data of both groups showed a high negative correlation between the intensity of the CRF stimulus and the duration of the PRP, which is consistent with the results of experiments in which a Method of Limits procedure was used. On the basis of this relationship between CRF current intensity and PRP duration a threshold for reinforcing brain stimulation was calculated.

Animals↗

PubMed1985

The transfer of alcohol tolerance, and its relation to reinforcement.

Four groups of five male social drinkers were trained on two different psychomotor tasks, a Pursuit Rotor (PR) and a Tracometer (T). They subsequently attended five drinking sessions where the same dose, 0.66 g absolute alcohol (ab alc)/kg, was administered. During these sessions, groups E and R received 'tolerance training' on the PR task by performing it under drug and receiving 25 cents reinforcement each time their score under alcohol was comparable to their drug-free level of achievement. The other two groups served as controls; group P performed the PR under alcohol but without reinforcement, and group A performed the PR with reinforcement but before alcohol was administered. The reduction of the drug-induced impairment of PR performance from Session 1-5 confirmed that groups E and R displayed significantly more tolerance than the controls. The effect of reinforcement on tolerance transfer to the T task was tested on Session 5. Groups E, P and A received reinforcement for T performance, and group R received no reinforcement. Since the E group displayed significantly more transfer of tolerance than the remaining three groups, the evidence confirmed the prediction that alcohol tolerance acquired via reinforced practice under drug transfers to a new task most readily when this reinforcement is also present.

Adult↗

PubMed2004

Responding for sucrose and wheel-running reinforcement: effect of body weight manipulation.

As body weight increases, the excitatory strength of a stimulus signaling an opportunity to run should weaken to a greater degree than that of a stimulus signaling an opportunity to eat. To test this hypothesis, six male albino Wistar rats were placed in running wheels and exposed to a fixed interval 30-s schedule that produced either a drop of 15% sucrose solution or the opportunity to run for 15s as reinforcing consequences for lever pressing. Each reinforcer type was signaled by a different stimulus. The effect of varying body weight on responding maintained by these two reinforcers was investigated by systematically increasing and decreasing post-session food amounts. The initial body weight was 335 g. Body weights were increased to approximately 445 g and subsequently returned to 335 g. As body weight increased, overall and local lever-pressing rates decreased while post-reinforcement pauses lengthened. Analysis of post-reinforcement pauses and local lever-pressing rates in terms of transitions between successive reinforcers revealed that local response rates in the presence of stimuli signaling upcoming wheel and sucrose reinforcers were similarly affected. However, pausing in the presence of the stimulus signaling a wheel-running reinforcer lengthened to a greater extent than did pausing in the presence of the stimulus signaling sucrose. This result suggests that as body weight approaches ad-lib levels, the likelihood of initiation of responding to obtain an opportunity to run approaches zero and the animal "rejects" the opportunity to run in a manner similar to the rejection of less preferred food items in studies of food selectivity.

Animals↗

PubMed2004

Does the terminal-link effect depend on duration or reinforcement rate?

Preference in concurrent chains for the richer terminal-link schedule becomes more extreme as the schedule values increase with their ratio held constant, a result known as the terminal-link effect. We report two experiments that attempt to determine whether this effect is related to terminal-link duration or the overall rate of reinforcement. These variables have been confounded in prior studies, but can be separated by comparing variable-duration schedules that end after a single reinforcer has been earned, with constant-duration schedules during which a variable number of reinforcers may be earned. In Experiment 1, the terminal-link effect was obtained with variable-duration schedules when duration and overall reinforcement rate were manipulated, but not with constant-duration schedules when overall reinforcement rate was changed with duration held constant. In Experiment 2, the terminal-link effect was obtained with constant-duration schedules when duration was manipulated with overall reinforcement rate held constant. Taken together, these results show that the terminal-link effect depends on changes in terminal-link duration, not overall reinforcement rate (or equivalently, average time to reinforcement). This accords with the account of the terminal-link effect provided by the contextual choice model [J. Exp. Anal. Behav. 61 (1994) 113] but not delay-reduction theory [J. Exp. Anal. Behav. 12 (1969) 723].

Animals↗

PubMed2006

Influence of budget and reinforcement location on risk-sensitive preference.

Little is known about the effect that procedural variables have on risk-sensitive preference. This study assessed the effect of procedural variables on pigeons' choice between a fixed and variable amount of reinforcement (amount risk) and, in a separate condition, between a fixed and variable delay until reinforcement (delay risk). Experiment 1 investigated the impact of water reinforcement and risk dimension when pigeons were in a restrictive budget, where access to water was less than that necessary to maintain current body weight, and a condition where the pigeons had ample access to water. Pigeons exhibited a greater tendency to prefer the variable alternative for delay risk than for amount risk in both restrictive and ample budgets. Varying water budget had no effect on risk preference. Experiment 2 investigated the influence of water reinforcer location while in a restrictive budget, in which reinforcers were delivered to a single location, two distinct locations, or a randomly selected location. With amount risk, pigeons were risk averse when reinforcers were delivered in separate or random locations and were indifferent to risk when delivered to a single location. With delay risk, pigeons were generally risk prone with no effect from reinforcement location. The finding that pigeons were risk averse when reinforcers were delivered to separate locations and were indifferent to risk when delivered to a single location offers a methodological explanation to the inconsistent findings in the literature with amount risk.

Animals↗

PubMed2005

Dietary restraint, anxiety, and the relative reinforcing value of snack food in non-obese women.

This study tested the independent and interactive effects of anxiety and dietary restraint on the relative reinforcing value of snack food. Thirty non-obese, female university students were assigned to one of four groups based on median split scores on measures of dietary restraint and state-anxiety: low-restraint/low-anxiety (n=7), low-restraint/high-anxiety (n=7), high-restraint/low-anxiety (n=9), and high-restraint/high-anxiety (n=7). Participants were provided the choice to earn points for palatable snack foods or fruits and vegetables using a computerized concurrent schedules choice task. The behavioural cost to gain access to snack foods increased across trials, whereas the cost to gain access to fruits and vegetables was held constant across trials. The relative reinforcing value of palatable snack food in relation to fruits and vegetables was defined as the total amount of points earned for snack food. Two-way analysis of covariance, with hunger and hedonic snack food ratings as covariates, showed that dietary restraint and anxiety had a significant interactive effect on the relative reinforcing value of snack food, indicating that the effect of anxiety on snack food reinforcement is moderated by dietary restraint. Specifically, the high-anxiety/low-restraint women found snack food significantly less reinforcing than low-anxiety/low-restraint women, but no differences emerged between high- and low-anxiety women with high-restraint. Neither restraint nor anxiety had an independent effect on the relative reinforcing value of snack food. These findings indicate that anxiety may have a suppressive effect on the relative reinforcing value of snack food in low-restrained eaters, but not an enhancing effect on snack food reinforcement in high-restrained eaters. Clinical implications of these findings are discussed.

Adult↗

PubMed2001

The impact of behavior-specific and behavior-nonspecific reinforcement on child compliance to mother directives.

Theories of child socialization differ with regard to the influence they attribute to behavior-specific reinforcement contingencies versus behavior-nonspecific reinforcement contingencies (i.e. social responsiveness). The present research investigated, at a within-individual level, the relationship between both types of reinforcement and child compliance with maternal directives. Behavior-specific reinforcement was defined as the history of reinforcement obtained by children for prior episodes of compliance and noncompliance to mother directives. Behavior-nonspecific reinforcement was defined as the history of reinforcement obtained by children for prosocial and aversive behaviors unrelated to mother directives. It was hypothesized that both reinforcement processes would be related to child responses to subsequent mother directives. The findings support these hypotheses. The discussion addresses caretaker social responsiveness as an intervention target of behavioral family therapy.

Behavior Therapy↗

PubMed2002

Differential effects of carbamazepine on negatively versus positively reinforced responding.

To assess its effects on negatively versus positively reinforced operant behavior, carbamazepine (CBZ) or vehicle was acutely administered to rats. Negative reinforcement baselines consisted of a free-operant avoidance task with 5-s shock-shock and 20-s response-shock intervals. Positive reinforcement baselines consisted of responding for food pellets on a variable interval 30-s schedule. Ascending dose-effect functions were established using CBZ for negatively reinforced responding (vehicle, 25, 50, 100 mg/kg ip) and positively reinforced responding (vehicle, 12.5, 25, 50, 100 mg/kg ip). Negatively reinforced responses and avoided shocks were significantly reduced by CBZ injections at 100 mg/kg. Positively reinforced responses and food pellet deliveries were significantly reduced by CBZ injections at 25, 50, and 100 mg/kg. The results show that CBZ has differential, dose-dependent effects on negatively versus positively reinforced responding.

Animals↗