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Results for “Reinforcement Schedule”

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PubMed1994

Methadone and feeding: sources of differences between home cage and operant chamber assessment procedures.

Methadone administration is reported to increase food intake in studies examining free feeding and to decrease food reinforced operant responding. In light of this apparent paradox, the present study evaluated methadone's effects on food reinforced operant responding under conditions more typical of free feeding studies than operant studies. The effect of methadone (5 mg/kg) on food intake was examined in rats maintained at 100% of their free feeding weights. Methadone did not increase food intake with food available under a fixed ratio 1 (FR 1) reinforcement schedule. Methadone did not alter response rate when each lever press produced a larger reinforcer (225 mg as opposed to 45 mg), but did increase food intake. When response requirements were changed from lever pressing to interruption of an infrared beam, increases in food intake following methadone administration were observed. Thus, the differences between methadone's effects on free feeding vs. operant chamber food intake may be due to procedural factors such as magnitude of reinforcement and response requirements.

Animals↗

PubMed1986

Task-specific effects of nicotine in rats. Intracranial self-stimulation and locomotor activity.

The acute effects of nicotine (0.03-1.0 mg/kg) were studied in a locomotor activity procedure and in a series of intracranial self-stimulation (ICSS) paradigms. Nicotine produced a dose-dependent decrease in locomotor activity. When animals were trained to lever-press for intracranial self-stimulation on a continuous reinforcement schedule (CRF), the drug was ineffective except at the 1.0 mg/kg dose, which produced a moderate decrease in the rate of responding. However, when animals were tested in a fixed-ratio:15 (FR:15) paradigm, nicotine produced a steep, biphasic dose-response curve. At the 0.1 mg/kg dose, the response rates were increased to approx. 60% above baseline, while at the 1.0 mg/kg dose, response rates were decreased to approx. 90% below baseline values. The effects of nicotine were also studied in an auto-titration procedure which measured the rewarding value of the stimulus. There was a decrease in performance at larger doses similar to that observed in the continuous reinforcement procedure, but there were no significant changes in the threshold for reinforcement. Nicotine did not produce any change in the detection threshold for stimulation of the brain. In acute studies, therefore, nicotine produced both stimulation and disruption of behavior, effects that were brought to light by the fixed-ratio schedule of reinforcement, and this may relate to the rewarding effects of nicotine.

Animals↗

PubMed1978

Second-order schedules of token reinforcement: comparisons of performance under fixed-ratio and variable-ratio exchange schedules.

Rats' lever pressing produced tokens according to a 20-response fixed-ratio schedule. Sequences of token schedules were reinforced under a second-order schedule by presentation of periods when tokens could be exchanged for food pellets. When the exchange period schedule was a six-response fixed ratio, patterns of completing the component token schedules were bivalued, with relatively long and frequent pauses marking the initiation of each new sequence. Altering the exchange period schedule to a six-response variable ratio resulted in sharp reductions in the frequency and duration of these initial pauses, and increases in overall rates of lever pressing. These results are comparable to those ordinarily obtained under simple fixed-ratio and variable-ratio schedules.

Journal Article↗

PubMed1997

Models of ratio schedule performance.

Predictions of P. R. Killeen's (1994) mathematical principles of reinforcement were tested for responding on ratio reinforcement schedules. The type of response key, the number of sessions per condition, and first vs. second half of a session had negligible effects on responding. Longer reinforcer durations and larger grain types engendered more responding, affecting primarily the parameter alpha (specific activation). Key pecking was faster than treadle pressing, affecting primarily the parameter delta (response time). Longer intertrial intervals led to higher overall response rates and shorter postreinforcement pauses and higher running rates, and ruled out some competing explanations. The treadle data required a distinction between the energetic requirements and rate-limiting properties of extended responses. The theory was extended to predict pause durations and run rates on ratio schedules.

Animals↗

PubMed1973

Facilitation and suppression of responding under temporally defined schedules of negative reinforcement.

Two parameters for scheduling aversive stimulus presentations were studied systematically by specifying concurrent and independent probabilities of electric shock delivery for the occurrence and for the non-occurrence of a lever-press response. After preliminary training on a free-operant shock-avoidance schedule, 16 rhesus monkeys were divided into four groups, each group being assigned one shock distribution on a continuum from fixed interval to a widely ranging variable interval. Within groups, each subject was successively exposed to three values of response-dependence of shock delivery on a continuum from response-independent shock to complete dependence of shock on response occurrence ("punishment"). Introduction of shock following avoidance training produced initial response facilitation followed by suppression. Responding during both the facilitation and suppression periods was maximal when the shock schedule was periodic and response independent. Responding decreased as the inter-shock intervals were made more variable across groups, and as shock delivery was made increasingly response dependent within individual subjects.

Journal Article↗

PubMed1980

Chronic ruminative vomiting: a comparison of four treatment procedures.

An experimental analysis of a case of chronic ruminative vomiting in a 15-year-old, profoundly retarded, Down's syndrome boy addressed the consequences of vomiting in the postmealtime environment. The experiment compared four treatments in each hour-long session using a multiple reinforcement schedule with order of the following procedures counterbalanced over days in a Latin square design: differential reinforcement of any behaviors other than vomiting (DRO) in which periods of no vomiting were followed by reinforcement and vomiting postponed reinforcement; differential reinforcement of specific behaviors alternative to vomiting (DRI) in which conjoint periods of no vomiting and sustained toy play were followed by reinforcement and the lack of either postponed reinforcement; extinction plus reinforcement of alternative behavior in which vomiting was ignored but toy play was reinforced; extinction in which vomiting was ignored. Data revealed an orderly dual cyclical pattern of vomiting throughout the day, with increased vomiting in the morning and immediately following food ingestion. Postluncheon treatments emphasizing reinforcement of alternative behavior were more successful in decreasing vomiting than DRO or extinction alone.

Adolescent↗

PubMed1995

Effects of reinforcer sweetness and the D2/D3 antagonist raclopride on progressive ratio operant performance.

Previous studies have reported that DA receptor antagonists suppress most behaviours; however, a paradoxical increase in performance may be seen in tests of operant or consummatory behaviours maintained by very sweet rewards, which lie on the descending limb of the inverted U-shaped concentration-performance function (i.e., under conditions where performance decreases as sweetness increases). Despite the low performance levels associated with very sweet reinforcers, preference studies indicate that they are nonetheless more rewarding. In the present study, the hypothesis that reinforcer efficacy is monotonically related to reinforcer sweetness was tested using a geometric progressive ratio reinforcement schedule, in which increasing numbers of responses were required to earn successive reinforcers (1, 2, 4, 8,.); the amount of work the animal emits in order to obtain an increasingly infrequent reinforcer is assumed to provide a measure of the magnitude of its rewarding effect. Three groups of rats were trained on this schedule, using as reinforcers food pellets containing 1%, 10% and 95% sucrose, respectively. Under conditions of continuous sucrose-pellet reinforcement, the highest response rates were maintained by the 10% sucrose pellets. However, under the progressive ratio schedule, performance was monotonically related to sucrose concentration. The dopamine D2/D3 receptor antagonist raclopride dose-dependently suppressed progressive ratio performance in all three groups.

Journal Article↗

PubMed1978

Picrotoxin-diazepam interaction in a behavioural schedule of differential reinforcement of low rates.

In rats working in a behavioural schedule of differential reinforcement of low rates (6 or 10 sec), picrotoxin (1 mg kg-1) decreased the number of premature responses and increased (in DRL 10 sec only) the number of rewarded responses. The effect of picrotoxin was antagonized by diazepam (2 mg kg-1). In contrast to picrotoxin, strychnine (1.5 mg kg-1) increased the number of premature responses.

Animals↗

PubMed1982

Sensory superstition on multiple interval schedules.

Pigeons were exposed to multiple schedules in which an irregular repeating sequence of five stimulus components was correlated with the same reinforcement schedule throughout. Stable, idiosyncratic, response-rate differences developed across components. Components were rank-ordered by response rate; an approximately linear relation was found between rank order and the deviation of mean response rate from the overall mean rate. Nonzero slopes of this line were found for multiple fixed-interval and variable-time schedules and for multiple variable-interval schedules both when number of reinforcements was the same in all components and when it varied. The steepest function slopes were found in the variable schedules with relatively long interfood intervals and relatively short component durations. When just one stimulus was correlated with all components of a multiple variable-interval schedule, the slope of the line was close to zero. The results suggest that food-rate differences may be induced initially by different reactions to the stimuli and subsequently maintained by food.

Animals↗

PubMed1980

Response deprivation and reinforcement in applied settings: A preliminary analysis.

First-grade children engaged in seatwork behaviors under reinforcement schedules established according to the Premack Principle and the Response Deprivation Hypothesis. Across two experiments, schedules were presented to the children in a counter-balanced fashion which fulfilled the conditions of one, both, or neither of the hypotheses. Duration of on-task math and coloring in Experiment 1 and on-task math and reading in Experiment 2 were the dependent variables. A modified ABA-type withdrawal design, including a condition to control for the noncontingent effects of a schedule, indicated an increase of on-task instrumental responding only in those schedules where the condition of response deprivation was present but not where it was absent, regardless of the probability differential between the instrumental and contingent responses. These results were consistent with laboratory findings supporting the necessity of response deprivation for producing the reinforcement effect in single response, instrumental schedules. However, the results of the control procedure were equivocal so the contribution of the contingent relationship between the responses to the increases in instrumental behavior could not be determined. Nevertheless, these results provided tentative support for the Response Deprivation Hypothesis as a new approach to establishing reinforcement schedules while indicating the need for further research in this area. The possible advantages of this technique for applied use were identified and discussed.

Journal Article↗

PubMed1983

The progressive ratio schedule as a model for studying the psychomotor stimulant activity of drugs in the rat.

Male Wistar rats were trained to press a lever with food reinforcement according to a continuously reinforced schedule (CRF). Afterwards, rats were subjected to three experimental sessions (30 min each) during which responding was rewarded according to a progressive ratio schedule (following an initial 2-min CRF period, the number of presses necessary for the pellet delivery was doubled every second minute). Responding during the first half of each session, i.e., pressing for food, was maintained at a significant level, whereas it was almost suppressed during the second part of the session. As compared to controls (200 +/- 20 presses/30 min) animals given amfonelic acid (0.5, 1 mg/kg IP), methylphenidate (4, 8 mg/kg IP), caffeine (16 mg/kg IP), cocaine (4 mg/kg IP), oxolinic acid (32 mg/kg IP), nomifensine (4 mg/kg IP), DR 250 (2, 4 mg/kg IP) and d-amphetamine (0.25, 0.5, 1 mg/kg IP) showed an increased rate of responding ranging from 400 to 950 presses/30 min. In contrast, apomorphine, MK 486 + L-dopa, trihexyphenidyl, imipramine, salbutamol and diazepam did not increase responding. These results suggested that this test is highly sensitive for psychomotor stimulants and perhaps for their ability to enhance the reinforcing value of the reward or stimuli associated with the reward. Such activity seemed related to a catecholaminergic substrate since the increase of responding induced by amphetamine was blocked by pimozide, d,l-propranolol and prazosin.

Animals↗

PubMed1998

Lesions of the midline thalamic nuclei impair classical conditioning under partial but not continuous reinforcement conditions.

Rabbits with lesions of the midline thalamic nuclei were compared to rabbits with sham lesions on classical eyeblink (EB) and heart rate (HR) conditioning. Separate groups of sham and lesioned animals received either 25, 50 or 100% reinforcement with a periorbital shock unconditioned stimulus. Animals with lesions showed slightly impaired EB conditioning, compared to sham animals, under the partial but not continuous reinforcement schedules. Midline lesions also reduced the magnitude of the decelerative HR conditioned response under partial but not continuous reinforcement conditions. These findings suggest that the midline thalamic nuclei, like the mediodorsal nucleus of the thalamus, process information required for response selection under non-optimal learning conditions.

Animals↗

PubMed1988

Fixed-ratio schedules of oral ethanol self-administration in inbred mouse strains.

Previous studies of ethanol reinforcement in BALB/cJ and C57BL/6J mice have shown that over a range of concentrations oral ethanol appeared to serve as a reinforcer only for the C57BL/6J mice. In the previous studies BALB/cJ mice maintained rates of responding for ethanol that only slightly exceeded the rates maintained by the vehicle, water. However, the quantity of ethanol consumed with the continuous reinforcement schedule (fixed ratio one) may have led to pharmacologically significant effects, given the high sensitivity to ethanol of this genotype. The present study tested whether and to what extent ethanol would maintain responding under increasing fixed ratio size in these two strains of mice at ethanol concentrations of 0%, 8%, and 16% (w/v). For the C57BL/6J mice, as fixed-ratio size increased from 1 to 2, 4, and 8, there were almost directly proportional increases in response rate at ethanol concentrations of 8% and 16% (w/v), but not at 0%. Post-session blood ethanol levels confirmed intake of pharmacologically significant quantities. The volume consumed per unit of body weight decreased as fixed-ratio size increased. For the BALB/cJ mice, at no condition did ethanol maintain responding at levels that significantly exceeded vehicle maintained responding. BALB/cJ mice did not differ from C57BL/6J mice as fixed-ratio size was increased during vehicle conditions. These results, along with earlier findings, demonstrate that ethanol can serve as a reinforcer for C57BL/6J mice but not in BALB/cJ mice over a range of schedule conditions. They further support the conclusion that genotype is an important determinant of ethanol reinforced behavior.

Alcohol Drinking↗

PubMed1984

Stimulus and reinforcer relativity in multiple schedules: Local and dimensional effects on sensitivity to reinforcement.

Pigeons' responses in two successive components of multiple schedules were reinforced according to variable-interval schedules of reinforcement that varied over five different conditions. Within each session of all conditions, line orientations of 0 degrees , 30 degrees , or 45 degrees in Component 1 alternated with orientations of 45 degrees , 60 degrees , or 90 degrees in Component 2. Response rates were recorded in three successive subintervals of each component. Ratios were taken between the response rate in each Component 1 line orientation and the response rate in each Component 2 orientation. These ratios were found to be power functions of the corresponding ratios of obtained reinforcement rates. Sensitivity of response ratios to changes in reinforcer ratios, given by the value of the exponent of the power function, increased systematically with increasing disparity between the dimensional values of orientation stimuli. In addition, sensitivity decreased systematically over successive subintervals of components, that is, with increasing time since component alternation. Dimensional and local (subinterval) effects interacted in that sensitivity increased with stimulus disparity to a far greater extent in the first subinterval than later in components. The data could be described by a combination of rectangular hyperbolae which attributed the interaction between local and dimensional effects to limits set by local effects on the extent that stimulus differences could affect sensitivity.

Journal Article↗

PubMed2005

Antisense-induced reduction in nucleus accumbens cyclic AMP response element binding protein attenuates cocaine reinforcement.

Repeated cocaine exposure up-regulates cyclic AMP signaling and increases the transcriptional activity of cyclic AMP response element binding protein (CREB) in the nucleus accumbens. To study the possibility that nucleus accumbens CREB activity regulates self-administration behavior, we tested the effects of a single, bilateral infusion of CREB antisense oligonucleotide into nucleus accumbens core and shell sub-regions on cocaine self-administration in rats. Nucleus accumbens core infusions of CREB antisense reduced CREB and the CREB-regulated immediate early gene brain-derived neurotrophic factor by 31 and 27%, respectively, but failed to alter levels of the homologous CREB family proteins cyclic AMP response element modulator and activating transcription factor 1, and had no effect on CREB levels in adjacent nucleus accumbens shell tissue. Similar infusions of CREB antisense in either core or shell produced a transient downward shift in cocaine self-administration dose-response curves on a fixed ratio 5 (five responses/injection) reinforcement schedule, indicating a reduction in cocaine reinforcement that fully recovered 3 days after treatment. CREB antisense also increased the threshold dose of cocaine required for reinstating cocaine self-administration, indicating that nucleus accumbens CREB levels regulate the incentive properties of cocaine. When access to cocaine was less restricted on a fixed ratio 1 schedule, infusion of CREB antisense in the core, but not shell, caused a transient (1-2 days) reduction in stabilized cocaine self-administration, but had no effect on responding maintained by sucrose pellets, indicating that basal CREB levels in the nucleus accumbens core regulate drug intake. None of these effects were produced by nucleus accumbens infusions of complementary sense oligonucleotide. These results suggest a necessary role for nucleus accumbens CREB activity in cocaine reinforcement, and, by converse analogy, up-regulation in CREB activity after chronic cocaine use could contribute to addiction-related increases in cocaine self-administration.

Animals↗

PubMed1980

Visual probability learning of institutionalized profoundly retarded adult males.

Eighteen profoundly retarded men were given repeated presentations of a two-choice visual discrimination using a modified Wisconsin General Test Apparatus and two probabilistic reinforcement schedules counterbalanced for order. Individuals received 240, 70:30 trials and up to as many 100:0 trials; when schedules were shifted, majority/minority (A1/A2) designations were reversed. The 100:0 results indicated preshift mean terminal rates that approached the reinforcement level and postshift rates that were inhibited by prior 70:30 training. The 70:30 results indicate learning only for those given a particular stimulus as their a1: overmatching prior to the shift that was reduced by previous 100:0 training to the matching level. Learning failures were explaiined in terms of attention to a preferred stimulus and the need for more trials, and areas for further inquiry were suggested.

Adult↗

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↗

PubMed1977

Attenuation of ethanol intake by contingent punishment of food-maintained responding.

Two food-deprived rats responded under a concurrent fixed-ratio 12 (food) fixed-ratio 1 (8% ethanol) reinforcement schedule in which a tone occurred during every second or every fourth interpellet interval. When ethanol-maintained lever presses during the presence of the tone shifted the food schedule to one in which electric shock punishment occurred, ethanol-maintained responding consistently decreased. The decrease in the frequency of ethanol-maintained responding varied directly with shock voltage from 25 to 100 V, and occurred during intervals with the tone present and absent. These results indicate that ethanol intake may be attenuated by contingent changes in a concurrent food schedule.

Alcohol Drinking↗