Schedules of reinforcement as determinants of human causality judgments and response rates.

Experiments examined the effect of relationships between a response and an outcome on human judgments of causal effectiveness. In Experiment 1, the time between outcomes obtained on a variable ratio (VR) schedule became the intervals for a yoked variable interval (VI) schedule. Response rates were higher on the VR than on the VI schedule. In Experiment 2, the number of responses required per outcome on a VR schedule were matched to that on a master VI 20-s schedule. Both ratings of causal effectiveness and response rates were higher in the VR schedule. In Experiment 3, tandem VI fixed-ratio (FR) schedules produced higher rates and judgments than equivalent conjunctive VI FR schedule. In Experiment 4, a VI schedule with a reinforcement requirement for a short interresponse time (IRT) produced higher rates and judgments than a simple VI schedule. These results corroborate the view that schedules are a determinant of both response rates and causal judgments. Few current theories of causal judgment predict this pattern of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Apprentissage vicariant dans une situation de conditionnement operant libre.

Investigated the quantitative and qualitative effects of fixed-ratio (FR) and fixed-interval (FI) reinforcement schedules on a free operant behavior acquired in a vicarious learning situation. 84 medical students underwent the direct or vicarious conditioning session. Complete vicarious acquisition was obtained with the FR schedule. With the FI schedule, response rates were lower than those recorded in the nonvicarious situation, but the temporal distribution of responses was inadequate and the behavioral pause was too brief following presentation of reinforcing stimuli. Observation of the entire conditioning session including the extinction phase did not lead to a more rapid extinction. It is suggested that the processes involved in the learning of the FR-controlled operant activity might be less complex and more immediately available to Ss, while in the FI condition the low perceptual saliency of relevant temporal factors might hinder the vicarious acquisition of the operant behavior. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular mechanisms resulting in pathogenic anti-mouse erythrocyte antibodies in New Zealand black mice

A procedure was developed with pigeons to extend the experimental analysis of punished behavior and the effects of anxiolytic drugs. Under this procedure the completion of a fixed-ratio requirement on a changeover key switched between two variable-interval schedules of reinforcement that were programmed on a second response key. Under one schedule, correlated with a green keylight, key pecks produced only food; under the second schedule, correlated with a red keylight, key pecks produced both food and electric shock. Pigeons were switched into the component with shock if they did not enter that component within 5 min. Parameter values of the variable-interval schedules were manipulated systematically and the effects of two clinically active anxiolytic drugs, buspirone and chlordiazepoxide, were examined. Responding was suppressed during the component with shock (punishment) and, under non-drug conditions, pigeons infrequently switched into the punishment component; changeover responses occurred rapidly when switched into the punishment component. Both buspirone (0.1-3.0 mg/kg) and chlordiazepoxide (3.0-30 mg/kg) increased punished responding at doses that had little effect on unpunished responding; d-amphetamine (0.3-5.6 mg/kg), which was studied only under one parameter of the variable-interval schedule, produced greater decreases in rates of punished responding than in unpunished responding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Response rate and sensitivity to the molar feedback function relating response and reinforcement rate on VI+ schedules of reinforcement.

In 5 experiments, the author examined rats' sensitivity to the molar feedback function relating response rate to reinforcement rate on schedules of reinforcement. These studies demonstrated that, at lower rates of responding, rats' performance on variable ratio (VR), variable interval (VI), and variable interval with linear feedback loop (VI+) schedules was determined largely by reinforcement of interresponse times; response rates were faster on VR than on both VI and VI+ schedules. In contrast, when procedures were adopted to maintain high rates of response, rats showed sensitivity to the molar characteristics of the schedules; they responded as fast on a VI+ schedule as on a VR schedule and faster on both of these schedules than on a yoked VI schedule. When the variance of response rate was manipulated, this factor was noted as an important element in determining sensitivity to the molar characteristics of the schedule. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of intermittent and constant punishment on resistance to punishment in a free operant situation for the albino rat.

Trained male Wistar albino rats (10 experimental and 9 control Ss) to barpress for food reinforcement in a 2-bar cyclic response chain situation. Responding on 1 bar led also to a punishment (footshock) on either an intermittent or constant schedule. Both punishment schedules led to increased responding on the nonpunished bar and to initial response suppression followed by recovery on the punished bar. For Ss on the intermittent schedule, the response increase on the nonpunished bar was seen only after a punishment on the other bar. Similar effects were found for transfer time between the 2 bars. The effects of punishment on response to both bars were more pronounced for the intermittent punishment groups. Results are discussed in terms of the motivational constructs of A. Amsel and of R. K. Banks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impulsivity in students with serious emotional disturbance: the interactive effects of reinforcer rate, delay, and quality

We conducted two studies extending basic matching research on self-control and impulsivity to the investigation of choices of students diagnosed as seriously emotionally disturbed. In Study 1 we examined the interaction between unequal rates of reinforcement and equal versus unequal delays to reinforcer access on performance of concurrently available sets of math problems. The results of a reversal design showed that when delays to reinforcer access were the same for both response alternatives, the time allocated to each was approximately proportional to obtained reinforcement. When the delays to reinforcer access differed between the response alternatives, there was a bias toward the response alternative and schedule with the lower delays, suggesting impulsivity (i.e., immediate reinforcer access overrode the effects of rate of reinforcement). In Study 2 we examined the interactive effects of reinforcer rate, quality, and delay. Conditions involving delayed access to the high-quality reinforcers on the rich schedule (with immediate access to low-quality reinforcers earned on the lean schedule) were alternated with immediate access to low-quality reinforcers on the rich schedule (with delayed access to high-quality reinforcers on the lean schedule) using a reversal design. With 1 student, reinforcer quality overrode the effects of both reinforcer rate and delay to reinforcer access. The other student tended to respond exclusively to the alternative associated with immediate access to reinforcers. The studies demonstrate a methodology based on matching theory for determining influential dimensions of reinforcers governing individuals' choices.     

A multiple-sequence variant of the multiple-baseline design: A strategy for analysis of sequence effects and treatment comparison.

The design logic and potential uses of a variant of the multiple-baseline design that implements multiple treatment sequences is described. The multiple-baseline multiple-sequence (MBL-MS) consists of 2 or more multiple-baseline designs that are interlaced with one another and include all possible sequences of the treatments. The counterbalanced sequencing of treatments permits observation of any sequence effects that are present. This sequencing can permit identification of an optimal treatment sequence and comparison of relative efficacy of treatments. This variation of the multiple baseline also extends the available treatment comparison designs by providing an additional design that does not require reversal or treatment or sequence effects. Because of vulnerability to ceiling and floor effects, the MBL-MS design appears to be primarily useful for the comparison of treatments that take several sessions to produce an optimal level of responding or when the behavior is not subject to floor or ceiling effects. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Behavioral contrast and behavioral momentum.

In Exp 1, 5 pigeons were trained to peck a key on multiple schedules of food reinforcement. The reinforcer rate was constant in 1 component and varied between conditions in the alternated component. In the constant component, steady-state response rate and its resistance to both prefeeding and extinction were inversely related to the reinforcer rate in the alternated component. Thus, resistance to both prefeeding and to extinction, like response rate, exhibits behavioral contrast. In Exp 2, a time-out period between schedule components eliminated contrast effects on steady-state response rate but not on resistance to extinction. The resistance-to-change results contradict expectations derived from current quantitative accounts of steady-state operant behavior and suggest instead that resistance to change depends on the contingency between component stimuli and reinforcers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Free-operant performance on variable interval schedules with a linear feedback loop: No evidence for molar sensitivities in rats.

Four experiments examined rats' sensitivity to molar and molecular factors on instrumental schedules of reinforcement. rats were exposed to a variable interval schedule with a positive feedback loop (VI+), such that faster responding led to a shorter interreinforcement interval. In Experiments 1 and 2, rats responded faster on a variable response (VR) schedule than on either a VI schedule matched for reinforcement rate or a VI + schedule matched for the feedback function. In Experiment 3, rats responded no differently on a VI schedule than they did on a VI+ schedule with equated rates of reinforcement. In Experiment 4, rats responded faster on a VI+ schedule with an interresponse time requirement yoked to that experienced on a VR schedule, than on a VI+ schedule with the same feedback function as the VR schedule. Taken together these results suggest that rats are more sensitive to the molecular than the molar properties of the schedules. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reinforcing values of interpretations and reflections in a quasi-therapeutic interview.

Investigated the effects of interpretations, reflections, and schedules of reinforcement in the conditioning of affective self-references operantly during a quasitherapy interview. Fifty high school students were randomly assigned to 1 of the 5 treatment groups: Group 1 received reflections on a continuous schedule; Group 2 received reflections under a fixed ratio; Group 3 received interpretations under a continuous schedule; Group 4 received interpretations under a fixed ratio; and Group 5, the control group, received no reinforcement for the correct response class. Results indicate that groups reinforced with reflections demonstrate a significantly higher rate of conditioning and extinction than groups reinforced with interpretations (p     

Effort as a determinant of choice in rats.

Studied the effect of response effort on rate of responding and choice behavior in a 2-bar situation in 2 experiments with 17 male Sprague-Dawley rats. Exp I used a limited test session and tested at a single FR ratio. Exp II employed a free behavior situation, in which total daily water intake was obtained by barpressing. Ratio requirements beginning with continuous reinforcement and followed by sessions of FR 5, 10, 20, 40, 80, 120, and 160 were tested. Relations between response rate and preference behavior were schedule dependent. On low-ratio schedules the highest response rates and preference were for the light bar. As the ratios were increased, however, response rates became higher and preference was switched to the heavy bar. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of d-amphetamine on responding of squirrel monkeys maintained under second-order schedules of food presentation, electric shock presentation or stimulus-shock termination

The effects of d-amphetamine (0.01-5.6 mg/kg i.m.) were studied on lever pressing of squirrel monkeys maintained under various second-order schedules by a visual stimulus (S) that, with separate monkeys, was occasionally paired with the presentation of either food, electric shock or with the termination of a stimulus in the presence of which shocks occurred. Under one condition, the first response after 5 min produced a 3-sec stimulus change and the fourth stimulus change was followed immediately by food delivery, electric shock presentation or by the termination of a stimulus in the presence of which shocks occurred [fixed-ratio (FR); fixed-interval (FI) [FR 4 (FI 5-min:S)]. The effects of d-amphetamine were also studied under the food- and shock-presentation schedules when food or shock occurred only once, at the end of each session, after completion of 53n 3-min fixed-intervals all of which ended with a brief stimulus change [FR 10 (FI 3-min : S)]. Under a third condition, each thirtieth response produced the 3-sec brief stimulus (FR 30 : S) and the first FR 30 completed after 5 min elapsed produced the stimulus followed by food or, with separate monkeys, electric shock [FI 5-min (FR 30:S)]. Low to intermediate doses of d-amphetamine (0.03-0.3 mg/kg) generally increased and higher doses (0.56-5.6 mg/kg) decreased responding under all conditions. The effects of d-amphetamine on responding maintained by brief stimuli under different types of second-order schedules are generally similar, regardless of the type of reinforcing event or particular second-order schedule.     

Fixed-ratio schedules increase generalized self-control: Preference for large rewards despite high effort or punishment.

Three experiments investigated the effects of FR reinforcement on generalized self-control involving high effort and punishment. In Experiment 1, rats received food in a runway for the completion of each round trip (continuous-reinforcement group) or every fifth round trip (FR group). Control rats received food at the same temporal intervals as these groups but without any instrumental requirement. When all rats were next given a series of choices between a large food reward requiring high lever force versus a small reward requiring low lever force, the FR rats showed the greatest self-control. In Experiments 2 and 3, rats were rewarded on a continuous or FR schedule followed by choice between a large food reward accompanied by intermittent shock vs a small or absent food reward without shock. The FR rats again showed the greatest self-control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinetics of matching.

Six male rats responded on concurrent variable interval (VI) schedules of brain stimulation reward in 2-trial sessions. Between trials, there was a 16-fold reversal in the relative rate of reward. In successive, narrow time windows, the authors compared the ratio of the times spent on the 2 levers to the ratio of the rewards received. Time-allocation ratios tracked wide, random fluctuations in the reward ratio. The adjustment to the midsession reversal in relative rate of reward was largely completed within 1 interreward interval on the leaner schedule. Both results were unaffected by a 16-fold change in the combined rates of reward. The large, rapid, scale-invariant shifts in time-allocation ratios that underlie matching behavior imply that the subjective relative rate of reward can be determined by a very few of the most recent interreward intervals and that this estimate can directly determine the ratio of the expected stay durations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response-independent events in the behavior stream

The metaphor of the behavior stream provides a framework for studying the effects of response-independent food presentations intruded into an environment in which operant responding of pigeons was maintained by variable-interval schedules. In the first two experiments, response rates were reduced when response-independent food was intruded during the variable-interval schedule according to a concomitantly present fixed-time schedule. These reductions were not always an orderly function of the percentage of response-dependent food. Negatively accelerated patterns of key pecking across the fixed-time period occurred in Experiment 1 under the concomitant fixed-time variable-interval schedules. In Experiment 2, positively and negatively accelerated and linear response patterns occurred even though the schedules were similar to those used in Experiment 1. The variable findings in the first two experiments led to three subsequent experiments that were designed to further illuminate the controlling variables of the effects of intruded response-independent events. When the fixed and variable schedules were correlated with distinct operanda by employing a concurrent fixed-interval variable-interval schedule (Experiment 3) or with distinct discriminative stimuli (Experiments 4 and 5), negatively accelerated response patterns were obtained. Even in these latter cases, however, the response patterns were a joint function of the physical separation of the two schedules and the ratio of fixed-time or fixed-interval to variable-interval schedule food presentations. The results of the five experiments are discussed in terms of the contributions of both reinforcement variables and discriminative stimuli in determining the effects of intruding response-independent food into a stream of operant behavior.     

Effects of serotonergic manipulations on cocaine self-administration in rats

Rats were trained to self-administer cocaine (0.5 mg/kg/infusion) and were then pretreated with the 5-HT1A agonist 8-OH-DPAT (0.125, 0.25 or 0.5 mg/kg, SC). 8-OH-DPAT pretreatment produced a decrease in reinforced response rates. When the effect of 8-OH-DPAT (0.5 mg/kg, SC) on responding for a range of cocaine doses was assessed, the drug produced a decrease in response rates when lower doses of cocaine served as the reinforcer. Fluoxetine (10 mg/kg, IV), an indirect 5-HT agonist, also reduced reinforced response rates for a low dose infusion of cocaine. Rates of responding for infusions of higher cocaine doses were not affected by fluoxetine pretreatment during an FR1 schedule of reinforcement. When an FR10 schedule of reinforcement was imposed, reinforced response rates for infusions of higher doses of cocaine were also reduced. Thus, under conditions that produce high rates of responding (low dose infusion or high ratio requirements for an infusion) fluoxetine reduced responding. This effect may be due to the effects at the 5-HT1A receptor, since 8-OH-DPAT produced a similar effect on cocaine self-administration. Given that the effects of these 5-HT agonists are observed only when low doses of cocaine serve as the reinforcer or when task demands are high, it is possible that the suppression of responding reflects an effect that is not specific to the reinforcing impact of cocaine. An alternative explanation for these effects incorporates a concept of unit cost/cocaine infusion that allows for direct comparison across studies that employ different reinforcement schedules.     

Acquisition of preference in concurrent chains: Comparing linear-operator and memory-representational models.

Two experiments were conducted to test predictions of 2 models for acquisition of preference in concurrent chains. Pigeons were trained with pairs of fixed-interval and variable-interval terminal-link schedules in a successive-reversal design. Results showed that acquisition rate was faster when fixed-interval schedules preceded and when variable-interval schedules followed the reversal and was approximately constant when the same pair of schedules was used. These results were predicted by both linear-operator and memory-representational models. However, only the linear-operator model predicted effects of schedule duration, Overall, these results demonstrated that a simple linear-operator model can account for the major features of preference acquisition in concurrent chains and suggest that choice in transition and steady state may provide convergent validation of a single delay-discounting function. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relative persistence of behavior: A fundamental measure of relative reinforcing effects.

Relative persistence of behavior is measured in terms of rates of behavior at a higher schedule value divided by rates of behavior at a lower schedule value and then multiplied by 100 to express the result as a percentage. Relative persistence of behavior is a direct function of reinforcer size over a broad range of values. In 1 study, food was the reinforcer; however, in most studies of persistence, drug reinforcers were used, and the drugs were taken orally or intravenously. A variety of reinforcing drugs were studied: barbiturates, opioids, psychomotor stimulants, a dissociative anesthetic, and alcohol. Both ratio and interval schedules were used to study relative persistence of behavior in human participants, male and female rhesus monkeys (Macaca mulatta), and rats. Thus, studies of persistence are based on results of an extensive set of conditions. The results support the proposition that relative persistence of behavior is a fundamental measure of relative reinforcing effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fixed-time schedules attenuate extinction-induced phenomena in the treatment of severe aberrant behavior

We compared the effects of extinction (EXT) and fixed-time (FT) schedules as treatment for severe problem behavior displayed by 3 individuals with developmental disabilities. First, functional analyses identified the reinforcers maintaining aberrant behavior for all 3 individuals. Next, EXT and FT schedules were compared using a multielement design. During EXT, the reinforcer maintaining problem behavior was withheld. During FT, the reinforcers were presented response independently at preset intervals. Results showed that FT schedules were generally more effective than EXT schedules in reducing aberrant behavior. FT schedules may be used in situations when extinction-induced phenomena are problematic.     

Reversal of nitrogen narcosis in rats by helium pressure

Changes in operant behavior were obtained for rats breathing nitrogen, helium, and both gases combined. Exposure to 12.9 ATA of nitrogen (O2 maintained at normobaric value of 0.2 ATA) produced complete cessation of responding on a fixed-ratio reinforcement schedule for 1 hour. The addition of elevated pressure of helium (12.1, 18.2, and 24.2 ATA) to the 12.9 ATA of nitrogen resulted in a reinstatement of responding during 1-hour hyperbaric exposures. The reinstatement of responding indicated a reversal of the nitrogen effects on behavior by increased helium pressures. The functional changes in behavior appeared to parallel the pressure produced reversal of anesthesia obtained at much higher pressures.