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PubMed2005

Effects of reinforcer probability, delay, and response requirements on the choices of rats and pigeons: possible species differences.

In Experiment 1 with rats, a left lever press led to a 5-s delay and then a possible reinforcer. A right lever press led to an adjusting delay and then a certain reinforcer. This delay was adjusted over trials to estimate an indifference point, or a delay at which the two alternatives were chosen about equally often. Indifference points increased as the probability of reinforcement for the left lever decreased. In some conditions with a 20% chance of food, a light above the left lever was lit during the 5-s delay on all trials, but in other conditions, the light was only lit on those trials that ended with food. Unlike previous results with pigeons, the presence or absence of the delay light on no-food trials had no effect on the rats' indifference points. In other conditions, the rats showed less preference for the 20% alternative when the time between trials was longer. In Experiment 2 with rats, fixed-interval schedules were used instead of simple delays, and the presence or absence of the fixed-interval requirement on no-food trials had no effect on the indifference points. In Experiment 3 with rats and Experiment 4 with pigeons, the animals chose between a fixed-ratio 8 schedule that led to food on 33% of the trials and an adjusting-ratio schedule with food on 100% of the trials. Surprisingly, the rats showed less preference for the 33% alternative in conditions in which the ratio requirement was omitted on no-food trials. For the pigeons, the presence or absence of the ratio requirement on no-food trials had little effect. The results suggest that there may be differences between rats and pigeons in how they respond in choice situations involving delayed and probabilistic reinforcers.

Animals↗
PubMed2005

A theory of attending and reinforcement in conditional discriminations.

A model of conditional discrimination performance (Davison & Nevin, 1999) is combined with the notion that unmeasured attending to the sample and comparison stimuli, in the steady state and during disruption, depends on reinforcement in the same way as predicted for overt free-operant responding by behavioral momentum theory (Nevin & Grace, 2000). The rate of observing behavior, a measurable accompaniment of attending, is well described by an equation for steady-state responding derived from momentum theory, and the resistance to change of observing conforms to predictions of momentum theory, supporting a key assumption of the model. When probabilities of attending are less than 1.0, the model accounts for some aspects of conditional-discrimination performance that posed problems for the Davison-Nevin model: (a) the effects of differential reinforcement on the allocation of responses to the comparison stimuli and on accuracy in several matching-to-sample and signal-detection tasks where the differences between the stimuli or responses were varied across conditions, (b) the effects of overall reinforcer rate on the asymptotic level and resistance to change of both response rate and accuracy of matching to sample in multiple schedules, and (c) the effects of fixed-ratio reinforcement on accuracy. Some tests and extensions of the model are suggested, and the role of unmeasured events in behavior theory is considered.

Attention↗
PubMed2005

Acquisition of cocaine self-administration with unsignaled delayed reinforcement in rhesus monkeys.

Six experimentally naive rhesus monkeys produced 0.01 mg/kg/infusion cocaine by lever pressing under a tandem fixed-ratio 1 differential-reinforcement-of-other-behavior schedule. One lever press initiated an unsignaled 15- or 30-s delay culminating in cocaine delivery. Each press made during the delay reset the delay interval. With two exceptions, responding was acquired and maintained at higher rates than responding on a second (inoperative) lever. For the exceptions, a cancellation contingency was arranged in which each formerly inoperative-lever response reset the tandem schedule. This manipulation reduced presses on the inoperative lever. Subsequently, the consequences of responding on the two levers were reversed, and the monkeys again responded at higher rates on the operative lever. As a comparison, 3 additional experimentally naive monkeys received response-independent cocaine deliveries. Although lever pressing was observed, it extinguished and was subsequently reestablished under the tandem schedule. The results suggest that although response-reinforcer contiguity is not required for cocaine to acquire reinforcing functions, a response-reinforcer relation appears necessary.

Animals↗
PubMed2006

Discriminability and sensitivity to reinforcer magnitude in a detection task.

Three pigeons discriminated between two sample stimuli (intensities of red light). The difficulty of the discrimination was varied over four levels. At each level, the relative reinforcer magnitude for the two correct responses was varied across conditions, and the reinforcer rates were equal. Within levels, discriminability between the sample stimuli did not change systematically as reinforcer magnitude varied. Across levels, the sensitivity of behavior to changes in the reinforcer-magnitude ratio decreased as the discriminability between the sample stimuli increased. Subsequent analysis showed that this relation was limited to performance following only one of the sample stimuli, the dim red light that remained constant across all conditions. Extant behavioral models of signal detection cannot easily accommodate these results.

Animals↗
PubMed1992

Use of reinforcement to increase independence in physical fitness performance of profoundly mentally retarded youth.

The purpose of this study was to examine the influence of verbal praise and verbal praise plus music or vibratory reinforcement on the level of independent performance on abdominal strength and endurance, lower back and hip flexibility, and upper body strength/endurance exercises of 12 profoundly mentally retarded, ambulatory youth, ages 10 to 18 years. A single-subject AB design with a control group was used to assess the difference in performance of physical fitness under the baseline condition of no reinforcement and under the two experimental conditions of verbal praise and verbal praise plus music or vibratory reinforcement. In contrast to previous results reported in the literature, verbal praise and verbal praise plus music or vibratory reinforcement were not effective in increasing the level of independence in performing selected physical fitness tasks.

Adolescent↗
PubMed1993

Reinforcement generalization as interaction between processes rather than events: absence of schedule-induced hyperdipsia in rats with histories of minimal food-water contiguity.

All scientific disciplines contain concepts that reflect interactions between their processes as well as between their units. The divergence process (generalization) applied to reinforcement predicts the existence of reinforcement generalization. Existence of this operation was suggested by the absence of schedule-induced hyperdipsia in rats for which the normal temporal contiguity between eating and drinking had been prevented. The results indicate that through generalization of reinforcement, which could explain the adjunctive class of behaviors, reinforcement of one process evokes comparable changes in other processes even if their overt correlates are not displayed contiguously.

Animals↗
PubMed2000

Effect of delay of reinforcement on superstitious inferences.

Temporal contiguity is positively associated with ease of detecting contingencies. When actions and outcomes are not contiguous, intervening responses might be strengthened by adventitious reinforcement. In the current study, participants engaged in a task where pressing 1 of 10 keys was reinforced either immediately or after various delays. Outcomes were scheduled either according to an FR 1 or FR 2 schedule. Participants also answered a question designed to assess their illusion of control. As the latency between the instrumental response and the reinforcer increased, participants attributed less importance to the instrumental response, attributed more importance to other nonessential responses, and began to show stereotyped patterns of responding. The illusion of control was positively related to the intricacy of such patterns. Results are discussed in terms of a contiguity which implies causality heuristic and the relationship of superstition with adventitious reinforcement and illusion of control.

Acoustic Stimulation↗
PubMed1990

Exploring the reinforcement of compliance with "do" and "don't" requests and the side effects: a partial replication and extension.

The side effects of reinforcing compliance to "do" and "don't" requests were examined in this study. The study was designed to do two things: (1) further establish that "do" and "don't" requests are functionally distinct and (2) determine which "don't" requests will show the same ability as "do" requests in effecting a change in topographically different inappropriate behaviors. Three children (2 boys and 1 girl), ages 5 yr. 2 mo. to 6 yr. 7 mo., participated. The design of the study was ABAC counterbalanced across subjects. With all three children reinforcement of "do" requests led to increased compliance with "do" requests without concurrent increase in compliance to "don't" requests. Also, reinforcing compliance to "don't" requests resulted in increased compliance to "don't" requests without concurrent increase in compliance to "do" requests. An undesirable side effect to the treatment was also noted. Two children showed a tendency to increase their rates of inappropriate behavior concurrent with increases in compliance to "don't" requests. Probable causes for this effect and concerns about the reinforcement of "don't" requests were discussed.

Behavior Therapy↗
PubMed2002

Cognitive theories as reinforcement history surrogates: the case of likelihood ratio models of human recognition memory.

B. F. Skinner (1977) once argued that cognitive theories are essentially surrogates for the organism's (usually unknown) reinforcement history. In this article, we argue that this notion applies rather directly to a class of likelihood ratio models of human recognition memory. The point is not that such models are fundamentally flawed or that they are not useful and should be abandoned. Instead, the point is that the role of reinforcement history in shaping memory decisions could help to explain what otherwise must be explained by assuming that subjects are inexplicably endowed with the relevant distributional information and computational abilities. To the degree that a role for an organism's reinforcement history is appreciated, the importance of animal memory research in understanding human memory comes into clearer focus. As Skinner was also fond of pointing out, it is only in the animal laboratory that an organism's history of reinforcement can be precisely controlled and its effects on behavior clearly understood.

Animals↗
PubMed2002

Failure of intravenous morphine to serve as an effective instrumental reinforcer in dopamine D2 receptor knock-out mice.

The rewarding effects of opiates are thought to be mediated through dopaminergic mechanisms in the ventral tegmental area, dopamine-independent mechanisms in the nucleus accumbens, or both. The purpose of the present study was to explore the contribution of dopamine to opiate-reinforced behavior using D2 receptor knock-out mice. Wild-type, heterozygous, and D2 knock-out mice were first trained to lever press for water reinforcement and then implanted with intravenous catheters. The ability of intravenously delivered morphine to maintain lever pressing in these mice was studied under two schedules of reinforcement: a fixed ratio 4 (FR4) schedule (saline, 0.1, 0.3, or 1.0 mg/kg, per injection) and a progressive ratio (PR) schedule (1.0 mg/kg, per injection). In the wild-type and heterozygous mice, FR4 behavior maintained by morphine injections was significantly greater than behavior maintained by vehicle injections. Response rate was inversely related to injection dose and increased significantly in the wild-type and heterozygous mice when the animals were placed on the PR schedule. In contrast, the knock-out mice did not respond more for morphine than for saline and did not respond more when increased ratios were required by the PR schedule. Thus, morphine served as a positive reinforcer in the wild-type and heterozygous mice but failed to do so in the knock-out mice. Under this range of doses and response requirements, the rewarding effects of morphine appear to depend critically on an intact D2 receptor system.

Animals↗
PubMed1999

The community-reinforcement approach.

The community-reinforcement approach (CRA) is an alcoholism treatment approach that aims to achieve abstinence by eliminating positive reinforcement for drinking and enhancing positive reinforcement for sobriety. CRA integrates several treatment components, including building the client's motivation to quit drinking, helping the client initiate sobriety, analyzing the client's drinking pattern, increasing positive reinforcement, learning new coping behaviors, and involving significant others in the recovery process. These components can be adjusted to the individual client's needs to achieve optimal treatment outcome. In addition, treatment outcome can be influenced by factors such as therapist style and initial treatment intensity. Several studies have provided evidence for CRA's effectiveness in achieving abstinence. Furthermore, CRA has been successfully integrated with a variety of other treatment approaches, such as family therapy and motivational interviewing, and has been tested in the treatment of other drug abuse.

Adaptation, Psychological↗
PubMed2000

Quantification of reinforcing effectiveness: comment on Meisch (2000)

R. A. Meisch (2000) introduces an innovative method for quantifying the reinforcing effectiveness of drugs and other substances. Advantages are that it models the persistence of drug use in humans and its persistence ratios are the same whether responding or consumption is measured. Data indicate that the method is sensitive to factors that affect drug self-administration. The measure's core feature is "the systematic variation of both reinforcer magnitude and schedule size" (Meisch, 2000, p. 347); however, the method may not be widely used with such extensive parametric analysis. Variation of only reinforcer magnitude (or dose/concentration) seems to produce similar results, and this abbreviated analysis is similar to the behavioral economic analysis of demand. When responding is plotted as a function of unit price (responses/milligram), the peak of the curve (where maximum responding occurs) is a measure of persistence. Further work will determine how these and other measures of reinforcing effectiveness agree.

Animals↗
PubMed2000

Intra-accumbens amphetamine increases the conditioned incentive salience of sucrose reward: enhancement of reward "wanting" without enhanced "liking" or response reinforcement.

Amphetamine microinjection into the nucleus accumbens shell enhanced the ability of a Pavlovian reward cue to trigger increased instrumental performance for sucrose reward in a pure conditioned incentive paradigm. Rats were first trained to press one of two levers to obtain sucrose pellets. They were separately conditioned to associate a Pavlovian cue (30 sec light) with free sucrose pellets. On test days, the rats received bilateral microinjection of intra-accumbens vehicle or amphetamine (0.0, 2.0, 10.0, or 20.0 microgram/0.5 microliter), and lever pressing was tested in the absence of any reinforcement contingency, while the Pavlovian cue alone was freely presented at intervals throughout the session. Amphetamine microinjection selectively potentiated the cue-elicited increase in sucrose-associated lever pressing, although instrumental responding was not reinforced by either sucrose or the cue during the test. Intra-accumbens amphetamine can therefore potentiate cue-triggered incentive motivation for reward in the absence of primary or secondary reinforcement. Using the taste reactivity measure of hedonic impact, it was shown that intra-accumbens amphetamine failed to increase positive hedonic reaction patterns elicited by sucrose (i.e., sucrose "liking") at doses that effectively increase sucrose "wanting." We conclude that nucleus accumbens dopamine specifically mediates the ability of reward cues to trigger "wanting" (incentive salience) for their associated rewards, independent of both hedonic impact and response reinforcement.

Amphetamine↗
PubMed1975

Separating the effects of response rate and reinforcement frequency in the rate-dependent effects of amphetamine and scopolamine on the schedule-controlled performance of rats and pigeons.

Rats and pigeons responded under three-component multiple schedules of food reinforcement. Each component was associated with a separate stimulus condition and a schedule that arranged food delivery intermittently for appropriately spaced responding. In the experiment with pigeons, three response rates were maintained with equal reinforcement frequency in the three components. With rats, the lowest response rate was associated with a higher reinforcement frequency. The effects of d-amphetamine in rats (0.05-0.6 mg) and pigeons (0.1-3.0 mg) were closely associated with the dose, and with the response rates that occurred under nondrug control conditions. Small doses of d-amphetamine increased low response rates proportionately more than moderate rates; moderate rates were increased proportionately more than were high rates. With larger doses, low rates were decreased proportionately less than were moderate rates, which in turn were decreased proportionately less than were high rates. Similar relations between drug effects and control rates were obtained in rats with scopolamine (0.0125-0.4 mg), with the exception that constant effects appeared at doses of 0.1 mg and greater. The present experiments, through manipulating response rate independently of reinforcement frequency, show that the rate-dependent effects of d-amphetamine and scopolamine are primarily response-rate-dependent drug effects.

Administration, Oral↗
PubMed1979

Reinforcing properties of nicocodine in the rhesus monkey.

The present study demonstrates that nicocodine is self-administered by the rhesus monkey in cross self-administration experiments. The minimum reinforcing dose is 10 times higher than that of codeine and 100 times higher than that of heroin. At reinforcing doses the rate of self-administered infusions of nicocodine is comparable with those of codeine. Further experiments are necessary to rank order nicocodine as to its positive reinforcing properties among the opiate-like compounds. On the other hand the present experiments demonstrate that nicocodine is an opium-like reinforcing compound.

Animals↗
PubMed2001

Haloperidol reduces stimulant and reinforcing effects of ethanol in social drinkers.

BACKGROUND: Despite abundant preclinical support for a role of dopamine (DA) in the stimulant-like and reinforcing effects of ethanol, there have been few studies directly investigating this mechanism in human subjects. This study examined the effect of a DA antagonist, haloperidol, on the subjective stimulant-like effects of acute doses of ethanol and on ethanol reinforcement in healthy human volunteers. It was hypothesized that a low dose of the DA D2/D3 antagonist haloperidol (3 mg) would attenuate stimulant-like subjective effects of ethanol (0.75 g/kg) and reduce the number of drinks chosen during a subsequent choice phase. METHODS: Seventeen healthy men and women, 21 to 35 years old, participated in four laboratory sessions conducted at 1-week intervals. During the four sessions they received, in randomized order under double-blind conditions, capsules containing haloperidol or placebo followed by three drinks containing ethanol (0.75 g/kg) or placebo, at 30-min intervals. Subjective and behavioral responses were measured before and after the beverages. After the third beverage, subjects could choose up to five additional doses of the beverage they had ingested. RESULTS: Haloperidol reduced the number of ethanol beverages subjects chose without altering placebo beverage choices. Haloperidol also dampened some of the subjective effects of ethanol, especially in subjects who experienced stimulation after ethanol. Haloperidol reduced stimulant-like and euphorigenic effects of ethanol in subjects who experienced stimulant effects (n = 8) but had no effect in subjects who did not experience stimulation from ethanol (n = 9). CONCLUSIONS: These findings suggest that DA plays a role in the stimulant-like, euphorigenic, and reinforcing qualities of ethanol in humans. However, the findings also raised new questions about the link between the subjective and reinforcing effects of ethanol.

Adult↗
PubMed2002

Second-order contrast based on the expectation of effort and reinforcement.

Pigeons prefer signals for reinforcement that require greater effort (or time) to obtain over those that require less effort to obtain (T. S. Clement, J. Feltus, D. H. Kaiser, & T. R. Zentall, 2000). Preference was attributed to contrast (or to the relatively greater improvement in conditions) produced by the appearance of the signal when it was preceded by greater effort. In Experiment 1, the authors of the present study demonstrated that the expectation of greater effort was sufficient to produce such a preference (a second-order contrast effect). In Experiments 2 and 3, low versus high probability of reinforcement was substituted for high versus low effort, respectively, with similar results. In Experiment 3, the authors found that the stimulus preference could be attributed to positive contrast (when the discriminative stimuli represented an improvement in the probability of reinforcement) and perhaps also negative contrast (when the discriminative stimuli represented reduction in the probability of reinforcement).

Animals↗
PubMed1992

Incentive learning following reinforcer devaluation is not conditional upon the motivational state during re-exposure.

Three experiments analysed the effect of re-exposure to the reinforcer following aversion conditioning on instrumental performance. In the first experiment, groups of hungry and thirsty rats were trained to press a lever for sucrose, which was then followed by a single injection of lithium chloride (LiCl). On the following day, half the animals in each motivational condition received re-exposure to the sucrose solution; the remaining animals were not re-exposed. In a subsequent extinction test animals that had received re-exposure to the sucrose pressed less than animals that were not re-exposed. Moreover, the effect of re-exposure to the sucrose solution was similar following training under hunger and thirst. In the remaining studies, animals were trained to lever-press for sucrose while either hungry or thirsty. They were then injected with LiCl and re-exposed to the sucrose while either hungry or thirsty, i.e. in the same or different motivational state employed during training, or they were not re-exposed. Lever pressing was then tested in extinction in the training motivational state. As in the first experiment, re-exposure to the reinforcer after aversion conditioning enhanced the magnitude of the reinforcer devaluation effect. More importantly, re-exposure to the sucrose produced a comparable effect on instrumental performance, whether re-exposure was given under the same or different motivational state to that employed during training. These results suggest that the instrumental reinforcer devaluation effect depends upon a process of incentive learning, but that this process is not conditional upon the current motivational state of the animal.

Animals↗