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Results for “Reinforcement Schedule”

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At least 649 records · Page 36Linked to original sources

PubMed1990

Conditioned suppression of the proboscis-extension response in young, middle-aged, and old Drosophila melanogaster flies: acquisition and extinction.

Young (7 days old), middle-aged (30 days old), and old (50 days old) Drosophila melanogaster males were used in an inhibitory conditioning of the proboscis-extension response. Two reinforcement schedules were applied, constant vs. partial. Partial reinforcement increased the number of trials needed to reach the learning criterion to the same extent in all age groups. Young flies needed fewer trials to reach the criterion than both middle-aged and old flies, which did not differ from each other. Extinction was delayed in the partial reinforcement groups by the same amount in all age groups. The slowest rate of extinction was observed in the old group and the fastest for the middle-aged flies. The results are discussed in connection with hypotheses that consider extinction an index either of behavioral rigidity or of strength of the initial learning.

Aging↗

PubMed1997

Negative side effects of noncontingent reinforcement.

Noncontingent reinforcement (NCR) has emerged as a treatment package for severe behavior problems. Although concerns about potential side effects (such as incidental reinforcement) have been raised, there have been few reported negative side effects in published studies to date. In this article, we report an NCR treatment evaluation for severe aggression that produced (a) an extinction burst and (b) incidental reinforcement. These side effects were evaluated by examining within-session response patterns and response distributions. As a solution, a brief omission contingency was added to the reinforcement schedule. The omission contingency resulted in decreased aggression rates.

Adolescent↗

PubMed1971

Matching to relative reinforcement frequency in multiple schedules with a short component duration.

Three pigeons performed on two-component multiple variable-interval variable-interval schedules of reinforcement. There were two independent variables: component duration and the relative frequency of reinforcement in a component. The component duration, which was always the same in both components, was varied over experimental conditions from 2 to 180 sec. Over these conditions, the relative frequency of reinforcement in a component was either 0.2 or 0.8 (+/-0.03). As the component duration was shortened, the relative frequency of responding in a component approached a value equal to the relative frequency of reinforcement in that component. When the relative frequency of reinforcement was varied over conditions in which the component duration was fixed at 5 sec, the relative frequency of responding in a component closely approximated the relative frequency of reinforcement in that component. That is, the familiar matching relationship, obtained previously only with concurrent schedules, was obtained in multiple schedules with a short component duration.

Journal Article↗

PubMedDate not supplied

The effects of chronic cadmium exposure on schedule controlled responding and conditioned suppression in the adult rat.

Adult rats fed daily rations of laboratory chow with added CdCl2 were tested for schedule controlled responding and conditioned suppression (conditioned emotional response-CER). Determinations of tissue Cd, levels of metallothionein, and the ratio of Cd in the tissue to the Cd-binding capacity of metallothionein also were made. Animals were exposed daily to either 5 mg/kg Cd (Group Cd-5), 1 mg/kg Cd (Group Cd-1), or no Cd (Group Control). An initial phase of training on a variable interval 2 min (VI-2) food reinforcement schedule lasting 40 sessions (1 session/day) was followed by CER training and then an interpolated period (100 days) of continued exposure but with no training. Schedule retraining was introduced for 21 sessions (1 session/day). The results showed no group differences during original schedule training. On the CER test, Group Cd-1 was found to exhibit less suppression (defined in terms of lever press rates) than controls to preaversive stimuli. Group Cd-5 showed significantly greater suppression to the primary aversive stimulus (shock) than the other two groups. Both treatment groups showed significantly lower lever press rates than controls on the schedule retraining task. These behavioral disturbances occurred commensurate with increases in non-metallothionein bound Cd in the liver, kidney, and small intestine.

Animals↗

PubMed1997

Learning the temporal dynamics of behavior.

This study presents a dynamic model of how animals learn to regulate their behavior under time-based reinforcement schedules. The model assumes a serial activation of behavioral states during the interreinforcement interval, an associative process linking the states with the operant response, and a rule mapping the activation of the states and their associative strength onto response rate or probability. The model fits data sets from fixed-interval schedules, the peak procedure, mixed fixed-interval schedules, and the bisection of temporal intervals. The major difficulties of the model came from experiments that suggest that under some conditions animals may time 2 intervals independently and simultaneously.

Animals↗

PubMed1971

Rate changes after unscheduled omission and presentation of reinforcement.

Changes in response rate similar to frustration effects were studied in a two-lever situation. Responding on one lever on a fixed-interval schedule produced access to water for 5 sec and an exteroceptive stimulus. In the presence of this stimulus, responding on another lever on a fixed-interval schedule produced access to water for 5 sec and terminated the stimulus. Occasional omission of a previously scheduled reinforcer after responding on the first lever resulted consistently in increases in rate on the second lever during the immediately succeeding interval. In another procedure, occasional presentation of a previously unscheduled reinforcer after responding on the first lever resulted consistently in decreases in rate on the second lever during the immediately succeeding interval. Changes occurred after the first omissions or presentations and were about the same in magnitude as the procedure continued over several sessions. Typically, an increase or decrease in rate was maintained throughout an entire 100-sec interval. Changes in rate on the second lever of approximately the same magnitude also occurred when rate on the first lever was near-zero under a schedule that differentially reinforced behavior other than lever pressing.

Journal Article↗

PubMed1973

Fixed-interval schedules of intravenous cocaine presentation in rats.

Fixed-interval schedules of intravenous cocaine presentation were examined as a function of injection dose (0.32 to 0.64 mg/kg) and interval duration (200 to 400 sec) in two rats. Cocaine was found to exert a dose-related temporal control over the initiation of responding that was unaffected by the fixed-interval contingency. Fixed-interval pause duration was linearly related to injection dose and was the same duration as the interresponse time found on continuous reinforcement schedules of cocaine presentation. The fixed-interval pause remained constant with changes in interval duration. Characteristic fixed-interval patterns of responding were observed. However, overall response rates were inversely related to injection dose and directly related to interval duration. Running response rates varied unsystematically with both variables. These findings are at variance with results typically found in studies of fixed-interval food and electric shock presentation.

Animals↗

PubMed1990

Effects of chlordiazepoxide and flumazenil on preference for punished and unpunished response alternatives in rats.

Male food-restricted hooded rats were trained to respond on a two-component multiple schedule. Reinforcement density was several times higher in one component than in the other. However, responses were intermittently punished with shock in the richer reinforcement component (conflict situation). Shock intensities were adjusted to produce mild and strong suppression of responding in two separate phases. Half of the rats controlled which component was operating (Preference group) and half did not (Yoked group). The effect of chlordiazepoxide (CDZ; 0, 1, 3, and 10 mg/kg; IP) was measured on component preference and response rate. Chlordiazepoxide increased both time spent in the conflict situation and response rate in that component. This is the first study employing a schedule that permitted these two behavioral indices to be measured independently in a conflict paradigm. Response rates were also increased in the unpunished response alternative, but to a lesser degree than in the conflict situation. The effects of CDZ were at least partially mediated by the benzodiazepine receptor because CDZ's effects were diminished by flumazenil (10 mg/kg; IP), a benzodiazepine antagonist.

Animals↗

PubMed1999

A signal detection analysis of auditory-frequency discrimination in the rat.

The frequency-discrimination behavior of rats in a simple go/no-go task was analyzed using the theory of signal detection. Discrimination acuity was studied and the receiver operating characteristic (ROC) was generated in subjects by varying the reinforcement schedule and signal probability. The detectability indices d', A', and sensitivity index (SI) and response-bias indices B" and responsivity index (RI) were used to describe behavior. A' gave the most suitable psychometric functions while RI best described response-bias behavior. Weber ratios were 6.25% +/- 0.23% at 5 kHz in three subjects. The best method to obtain the ROC was to vary the probability with which subjects were reinforced. The ROC in two subjects demonstrated classical forms; in another subject, the function was asymmetric to the extent that detectability was not independent of response bias. Subjects altered their decision criterion in reporting a signal from trial to trial depending on previous trial events. On any given trial, subjects made a decision in one of several "decision states." Variables that influenced decision states included previous reinforcement and timeouts. The data indicate that timeouts may not be a useful feature in go/no-go tasks. The identification of multiple-decision states within a single behavioral session is a convenient method to generate the ROC without expressly manipulating experimental conditions.

Animals↗

PubMed1986

Modification of REM sleep behavior by REMs contingent auditory stimulation in man.

Following studies about supposed relationship between rapid eye movement sleep (REM sleep) and learning, a new approach, based on operant conditioning is introduced. We demonstrate that rapid eye movements (REMs) contingent auditory stimulation in man leads to some consistent (quantitative and qualitative) modifications of REM sleep behavior. Stimulating REMs in the frame of a continuous reinforcement schedule increases total REM sleep duration but decreases REMs density, and modifies hemispheric EEG symmetry. The contrasting effects of such sensory stimulations and results related to information processing hypothesis are discussed.

Acoustic Stimulation↗

PubMed1994

The effects of control on stress-induced gastric erosions: the use of active shuttle-box avoidance learning with yoked controls.

The aim of the present study was to investigate effects of instrumental control on the development of stress-induced gastric erosions by using a shuttle-box paradigm with yoked controls. In Experiment 1 the learning conditions had a reinforcement ratio of only 70% to increase stress during the short-term learning session. No significant differences of the mean cumulative length of gastric erosions between active avoiding and yoked groups were found. Experiment 2 tested three different reinforcement conditions (70%, 90%, 100%) with yoked groups. Again, no significant differences of the mean cumulative length of erosions between active avoiding and yoked control groups were obtained. Instead, the length of erosions decreased with increasing reinforcement. Taken together, the data show that the frequency of unavoided noxious stimuli as a function of the reinforcement schedule can be seen as a major influence on the development of gastric erosions in a shuttle-box paradigm.

Animals↗

PubMed2002

Preference and resistance to change with constant- and variable-duration terminal links: independence of reinforcement rate and magnitude.

Pigeons responded in a three-component multiple concurrent-chains procedure in which the variable-interval reinforcement schedules were the same across components but magnitudes differed across components. The terminal links were arranged either as a variable delay followed by presentation of a reinforcer ("variable duration") or as a fixed period of access to the schedule during which a variable number of reinforcers could be earned ("constant duration"). Relative reinforcement rate was varied parametrically across both types of conditions. After baseline training in each condition, resistance to change of terminal-link responding was assessed by delivering food during the initial links according to a variable-time schedule. Both preference and resistance to change were more sensitive to reinforcement-rate differences in the constant-duration conditions. Sensitivities of preference and resistance to change to relative reinforcement rate did not change depending on relative reinforcement magnitude. Taken together, these results confirm and extend those of prior studies, and suggest that reinforcement rate and magnitude combine additively to determine preference and resistance to change. A single structural relation linking preference and resistance to change describes all the data from this and several related studies.

Animals↗

PubMed2006

The influence of prior choices on current choice.

Three pigeons chose between random-interval (RI) and tandem, continuous-reinforcement, fixed-interval (crf-FI) reinforcement schedules by pecking either of two keys. As long as a pigeon pecked on the RI key, both keys remained available. If a pigeon pecked on the crf-FI key, then the RI key became unavailable and the crf-FI timer began to time out. With this procedure, once the RI key was initially pecked, the prospective value of both alternatives remained constant regardless of time spent pecking on the RI key without reinforcement (RI waiting time). Despite this constancy, the rate at which pigeons switched from the RI to the crf-FI decreased sharply as RI waiting time increased. That is, prior choices influenced current choice-an exercise effect. It is argued that such influence (independent of reinforcement contingencies) may serve as a sunk-cost commitment device in self-control situations. In a second experiment, extinction was programmed if RI waiting time exceeded a certain value. Rate of switching to the crf-FI first decreased and then increased as the extinction point approached, showing sensitivity to both prior choices and reinforcement contingencies. In a third experiment, crf-FI availability was limited to a brief window during the RI waiting time. When constrained in this way, switching occurred at a high rate regardless of when, during the RI waiting time, the crf-FI became available.

Animals↗

PubMed2001

A dopamine partial agonist and antagonist block amphetamine self-administration in a progressive ratio schedule.

A recently characterized class of compounds, dopamine partial agonists, have been suggested as potential therapeutic candidates for pharmacological intervention in psychostimulant addiction. These drugs bind to dopamine receptors with high affinity and low intrinsic activity and are thought to behave as functional antagonists in conditions of high dopaminergic tone, and as agonists in conditions of low receptor occupancy by dopamine. The aim of the present study was to characterize the effects of terguride, a partial dopamine agonist at the D2 receptor subtype, on intravenous self-administration of amphetamine in a progressive ratio schedule and to compare it with the effects produced by the dopamine D2 antagonist eticlopride and the dopamine D2 full agonist quinpirole. Terguride at the doses of 0.2 and 0.4 mg/kg i.p. significantly decreased the maximum number of responses delivered for a single injection of amphetamine ("breaking point"), an effect similar to that produced by the antagonist eticlopride (0.01-0.1 mg/kg s.c.). In contrast, administration of quinpirole (0.1-1 mg/kg s.c.) did not significantly modify the breaking point for amphetamine responding. Also, terguride dose-dependently increased responding for amphetamine self-administration on a continuous reinforcement schedule. These data further confirm the effects of terguride on psychostimulant self-administration and indicate that under these conditions partial dopamine agonists act as functional dopamine receptor antagonists.

Amphetamine↗

PubMed1979

Noradrenaline, fear and extinction.

It has been suggested that noradrenaline in the central nervous system is involved in fear and anxiety. To test this postulate extensive depletion of ascending noradrenaline systems was accomplished by intracerebral injection of the selective neurotoxin 6-hydroxydopamine. Fear and anxiety were assessed using a Sidman avoidance task and a conditioned emotional response paradigm. No alteration in fear motivated acquisition learning of either of these tasks were detected. Resistance to extinction was seen on the conditioned emotional task, perhaps because of its continuously reinforced nature, but not on the Sidman avoidance, perhaps as a consequence of the reinforcement contingencies which render this task more similar to a partially reinforced schedule. No evidence for a role of ascending noradrenaline systems in fear or anxiety was hence obtained, but a further demonstration of a role in extinction processes was found.

Animals↗

PubMed1996

Schedule-controlled operant behavior of rats following oral administration of perchloroethylene: time course and relationship to blood and brain solvent levels.

Previous studies have indicated that human exposure to perchloroethylene (PCE) produces subtle behavioral changes and other neurological effects at concentration at or below the current occupational exposure limit. Since comparable effects in animals may be reflected by changes in schedule-controlled operant behavior, the ability of orally administered PCE to alter fixed-ratio (FR) responding for a food reward was investigated in male Sprague-Dawley rats. Furthermore, since behavioral effects of solvents are likely to be more closely related to blood or target tissue (i.e, brain) concentrations than administered dose, the relationship between the pharmacokinetic distribution of PCE and its effects on operant responding was also evaluated. Rats trained to lever-press for evaporated milk on an FR-40 reinforcement schedule were gavaged with 160 or 480 mg/kg PCE and immediately placed in an operant test cage for 90 min. Separate animals gavaged with equivalent doses of PCE were used to determine profiles of blood and brain concentrations versus time. Perchloroethylene produced changes in responding that varied not only with dose but also among animals receiving the same dose. Changes in the response rates of rats receiving 160 mg/kg PCE were either not readily apparent, restricted to the first 5 min of the operant session, or attributable to gavage stress and the dosing vehicle. However, 480 mg/kg produced either an immediate suppression of responding for 15-30 min before a rapid recovery to control rates or a complete elimination of lever-pressing for the majority of the operant session. Although the two doses of PCE produced markedly different effects on operant behavior during the first 30 min of exposure, differences in brain concentrations of PCE were minimal. Furthermore, the majority of animals receiving 480 mg/kg PCE fully recovered from response suppression while blood and brain levels of the solvent continued to rise. Thus, relationships between blood and brain PCE levels and performance impairment were not discernible over the monitored time course. Since the rapid onset of response suppression suggests that the precipitating event occurs within the first few minutes of exposure, it is possible that altered responding is related to the rate of increase in blood or brain concentrations rather than the absolute solvent concentrations themselves. The relationship between the pharmacokinetic distribution of solvents and their effects on the central nervous system is obviously complex and may involve acute neuronal adaptation as well as the dynamics of solvent distribution among the various body compartments.

Administration, Oral↗

PubMed2001

Transitional choice behavior in concurrent-chain schedules.

The choice responses of four pigeons were examined in 20 periods of transition in a concurrent-chain procedure with variable-interval schedules as initial links and fixed delays to reinforcement as terminal links. In some conditions, the delays to reinforcement were different for the two terminal links, and changes in preference were recorded after the delays for the two response keys were switched. In other conditions, the reinforcer delays were equal for the two keys, but which key delivered 80% of the reinforcers was periodically switched. Choice proportions changed more quickly after a switch in reinforcement percentages than after a switch in the delays, thereby contradicting the hypothesis that faster changes would occur when the switch in conditions was easier to discriminate. Analyses of response sequences showed that the effects of individual reinforcers were larger and lasted longer in conditions with changing reinforcement percentages than in conditions with changing terminal-link delays. Rates of change in choice behavior do not appear to be limited by the unpredictability of variable reinforcement schedules, because the changes in behavior were slow and gradual even when there was a large and sudden change in reinforcer delays.

Journal Article↗

PubMed2004

Extracellular level of basolateral amygdalar dopamine responding to reversal of appetitive-conditioned discrimination in young and old rats.

Young and old rats, aged 3 and 24 months old, respectively, were conditioned to press a lever under lamp-on conditions for reward acquisition and lamp-off for no reward using a variable interval reinforcement schedule that averaged 15 s; i.e., the minimal requirement was 4 responses/min. Over a 30-day period, young and old groups showed increased response to lamp-on from 22 to 35/min and from 10 to 23/min, respectively, and shortened response to lamp-off after initial training. Response to lamp-on as a percentage of total response to lamp-on and -off (the discrimination ratio) was over 80%. For the next 30 days, reversal learning was imposed to reinforce discrimination of the lamp-off state. Young rats showed a steadily increasing discrimination ratio from 40% to 70%, and old rats from 30% to 60%. In comparison with the initial training, young rats showed a total response increase from 50% to 60%, while old rats showed an approximately 5% decrease without loss of reward-obtaining efficiency. In vivo microdialysis during reversal revealed that young rats had higher dopamine transmission in the basolateral amygdala than old rats. The dopamine level was positively correlated with the number of responses to state of reward in young rats and negatively with the numbers of both NRF and RF responses to lamp-on and -off states in old rats. These results suggest that in reversal discrimination, basolateral amygdalar dopamine efflux correlates with the manner of age-related conditioned response rather than the ability to learn.

Age Factors↗