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Results for “Reinforcement Schedule”

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At least 433 records · Page 24Linked to original sources

PubMed1971

Stimulus functions in some chained fixed-ratio schedules of reinforcement.

For two pigeons, behavior was compared in equivalent two-link chained and tandem schedules in which 100 responses were required for food reinforcement but the responses required in the two links of the chained schedule were varied over the values 2-98, 50-50, and 98-2. Initial pausing, response rate in each link, and the total time to complete each ratio were recorded. In chained components, initial-link pausing (for both birds) and total time to complete the ratio (for one bird) were generally shorter when the response requirement was 2-98 than when it was 50-50 or 98-2; for terminal-link pausing this relationship was reversed for both birds. There were also systematic changes in behavior in tandem components, and in the relationship between behavior in chained and tandem components. The results are discussed in terms of conditioned reinforcement.

Journal Article↗

PubMed1987

Interaction between naloxone, chlordiazepoxide and valproic acid evaluated by emotional operant behaviour in the rat.

The effects of chlordiazepoxide (CDP, 5 mg/kg i.p.), the sodium salt of valproic acid (VPA, 200 mg/kg i.p.) and naloxone (Nx, 1 mg/kg s.c.) alone and CDP-Nx, VPA-Nx association on schedule controlled behaviour with signalled unpunished and punished periods, were investigated. Our results show that CDP and VPA under both the unemotional (variable ratio reinforcement schedule 20%) and the emotional (continuous reinforced schedule associated with electric shock) components significantly increase responding in the Skinner box. Nx, on the multiple schedule, non-significantly reduces responding under both components. With CDP-Nx association the increase in responding under the unemotional component is less than in the case of the benzodiazepine alone, while under the emotional component the increase in responding is not appreciably affected. With the VPA-Nx association the responding rate is lower than that of the control under the unemotional component while under the emotional component the increase in responding is reduced compared to the VPA alone. The higher rates of unemotional and emotional responding with both CDP and VPA depend on the dipsogenic and disinhibiting effects by both drugs. The different rate of emotional and unemotional responding with CDP-Nx and VPA-Nx associations indicates a specific influence on GABAergic and other systems by CDP and VPA.

Animals↗

PubMedDate not supplied

Effects of triethyltin on responding of mice under a multiple schedule of reinforcement.

The lethality and behavioral effects of triethyltin (TET) were determined in adult, male BALB/c mice. Following a single IP dose of TET (10, 12.5 or 15 mg/kg), the lethality was determined at 24-hr intervals. By 144 hr after TET administration, lethality had risen to greater than 90% in the groups receiving the 12.5 and 15 mg/kg and 20% (6/30) in the group which received 10 mg/kg. No additional deaths were observed over the remainder of the two week observation period. The behavioral effects of 5, 7.5 or 10 mg/kg were determined in mice trained to respond under a multiple fixed-ratio 30, fixed-interval 600-sec schedule of milk presentation. At 3 hr after TET administration, the rate of responding was decreased at all three doses. However, by 27 hr after 5 or 7.5 mg/kg TET the rate of responding had returned to pre-injection control values while the responding of the mice in the 10 mg/kg group did not return to pre-injection control values until 51 hr after administration. In a separate group of mice, 7.5 mg/kg was administered at 2 week intervals for a total of 5 separate administrations. No evidence for a cumulative or diminished behavioral effect was observed. Neuropathological examination revealed a direct dose and time related pathology in the white matter of the CNS. Maximal edematous vacuolar change was observed 72 hr after TET administration. Such morphological changes, however, were totally absent 12 days after a single 10 mg/kg exposure. Multiple exposure to TET (7.5 mg/kg) at 2 week intervals for 10 weeks showed only minimal morphological alterations in the brain.

Animals↗

PubMed2004

Psychological distance to reward: equating the number of stimulus and response segments.

Psychological distance to reward, or the segmentation effect, refers to the preference for a terminal link of a concurrent-chains schedule consisting of a simple reinforcement schedule (e.g. fixed interval [FI] 30s) relative to its chained-schedule counterpart (e.g. chained FI 15s FI 15s). This experiment was conducted to examine whether the segmentation effect is due to the number of terminal-link stimulus and response segments per se. Three pigeons pecked under a concurrent-chains schedule in which identical variable-interval (VI) schedules operated in the initial links. In each session, half the terminal-link entries followed one initial-link key and the other half followed the other initial-link key. The initial-link keys correlated with the different terminal links were manipulated across conditions. In the first three conditions, each terminal link contained a chained fixed-time (FT) FT schedule, and in the final three conditions, each terminal link contained a chained FI FI schedule. In each condition, in one terminal link (alternating), the order of two key colors correlated with the different schedule segments alternated across terminal-link entries, whereas in the other terminal link (constant), the order of two other key colors was identical for each entry. With the chained FT FT schedule terminal links, there was indifference between the alternating and constant terminal links within and across pigeons, as indexed by initial-link choice proportions. In addition, terminal-link response rates were relatively low. With the chained FI FI schedule terminal links, for each pigeon, there was relatively more preference for the alternating terminal link and terminal-link response rates increased relative to conditions with the chained FT FT schedule terminal links. These data suggest that the segmentation effect is not due simply to the number of terminal-link stimulus or response segments per se, but rather to a required period of responding during a stimulus segment that never is paired with reinforcement.

Adaptation, Psychological↗

PubMed2005

Effects of stimulus variation on the reinforcing capability of nonpreferred stimuli.

We examined the effects of stimulus (reinforcer) variation in several different contexts. In Study 1, we identified high-quality (HQ) and low-quality (LQ) stimuli based on results of a paired-stimulus assessment and examined their effects when available under concurrent-reinforcement schedules for 8 participants. No participants showed preference for the LQ stimuli when compared singly or in a varied arrangement to the HQ stimulus. In Study 2, we identified nonpreferred (NP) stimuli based on results of a single-stimulus assessment and examined their effects when available under single-reinforcement schedules for 3 participants. Results of Study 2 were mixed. One participant's data indicated that the varied presentation of NP stimuli produced a modest improvement in performance over that observed when the stimuli were presented singly. By contrast, a second participant's data showed no facilitative effect for the varied delivery of NP stimuli and that the inclusion of an HQ stimulus in the varied arrangement obscured the reinforcing effects of the HQ stimulus. The 3rd participant's data showed no effect for the varied delivery of NP stimuli but an apparent facilitative effect when an HQ stimulus was included in the varied arrangement, which was attributable solely to the presence of the HQ stimulus.

Adult↗

PubMed2002

The effects of brain injury on choice and sensitivity to remote consequences: deficits in discriminating response-consequence relations.

PRIMARY OBJECTIVE: One characteristic of some decision-making deficits is a failure to respond adaptively to consequences that follow choices. This investigation examined the sensitivity of choice to remote consequences with a high overall reinforcement rate and proximal consequences with a low overall reinforcement rate. METHODS: Three control and three subjects with brain injury made repeated choices between two reinforcement schedules: a fixed time schedule (FT) that delayed reinforcement by 12 seconds, and a progressive time schedule (PT) that progressively increased reinforcement delay by 2 seconds with each consecutive choice and reset to 0 seconds with each choice of the fixed schedule. Switching to the FT schedule at PT 6 seconds maximized overall reinforcement rate. RESULTS: Subjects with brain injury were less sensitive to contingencies and earned less reinforcement relative to controls because switching occurred at lengthy PT delays (delays far exceeding 6 seconds). CONCLUSIONS: Some deficits in decision-making and adaptation following injury may reflect a reduction in sensitivity to contingencies.

Adult↗

PubMed1995

Effects of different food-reinforcement histories on cocaine self-administration by rhesus monkeys.

The purpose of the present study was to examine whether a history of responding under food reinforcement schedules that generated either high or low response rates would influence the acquisition and maintenance of cocaine self-administration. Eight experimentally naive rhesus monkeys were initially trained to respond on the right lever under either a fixed-ratio (FR) 50 or interresponse times (IRT) > 30-s schedule of food reinforcement. After 65 sessions of food-maintained responding, monkeys were surgically prepared with indwelling intravenous catheters and cocaine 0.03 mg/kg per injection (IV) was available on the left lever under a fixed-interval (FI) 5-min schedule. After at least 60 consecutive sessions at this dose, a cocaine dose-response curve (saline, 0.01-0.3 mg/kg per injection) was determined. The FR 50 schedule generated high rates of food-maintained responding (90.1 +/- 6.2 responses/min), while response rates under the IRT > 30-s schedule were low (1.9 +/- 0.1 responses/min). Across the 60 consecutive sessions under the FI 5-min schedule, linear changes in response rates and cocaine intake were significantly different between FR- and IRT-history monkeys. FR-history monkeys responded at higher rates than IRT-history subjects, while cocaine intake during the first 15 sessions was lower in FR- compared to IRT-history monkeys. Rates of cocaine-maintained responding after food-reinforcement histories were compared to response rates of monkeys initially trained to self-administer cocaine under an FI 5-min schedule (Nader and Reboussin 1994).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Determinants of human performance on concurrent schedules.

Six experiments, each with 5 human adults, were conducted to investigate the determinants of human performance on multiple concurrent variable-interval schedules. A two-key procedure was employed in which subjects' key presses produced points exchangeable for money. Variables manipulated across experiments were (a) changeover delay (Experiments 2, 4, and 6), (b) ordinal cues related to scheduled reinforcement frequencies (Experiments 3 and 4), and (c) instructions describing the ordinal relations between schedule-correlated stimuli and scheduled reinforcement frequency (Experiments 5 and 6). The performances of only 13 of the 30 subjects could be described by the generalized matching equation and were within a range of values typical of those reported in the animal literature. Eight subjects showed indifference, 9 undermatched, 7 approximated matching, 3 overmatched, and a further 3 responded exclusively to the richer component of the concurrent schedules. These differing modes of responding were closely related to the different types of performance rules reported by subjects in postexperimental questionnaires. The results are in good agreement with those from studies of human performance on single schedules, suggesting that rule-governed behavior, in interaction with contingencies, may be an important determinant of human choice.

Adolescent↗

PubMed1997

The effects of cocaine on operant responding for food in several strains of mice.

The availability of numerous genetically homogenous mouse strains permits the analysis of genetic influences on behavior and also behavioral sensitivity (responsivity) to drugs of abuse. The current study was conducted to characterize discriminated operant responding for food in four inbred strains (Balb/cByJ, DBA/2J, C57BL/6J, SJL/J), an F1 Hybrid (C57BL/6xSJL), and one outbred strain (CD1) of mouse. The effect of cocaine on this operant behavior was also examined. Initially, all animals were trained to nosepoke for food on a continuous reinforcement schedule. The minimum response requirement for reinforcement was increased every 5 days until the animals were responding on an FR-15 schedule of reinforcement. All strains increased operant responding as the schedule of reinforcement was raised. However, significant differences in response rate and discrimination learning were observed among the various strains of mice. Cocaine administration reduced operant responding for food in Balb/cByJ, C57BL/6J, C57BL/6xSJL/J and CD1 mice at a dose of 15.0 mg/kg, whereas higher doses were required in DBA/2J mice (30.0 mg/kg) and SJL/J mice (56.0 mg/kg). These results suggest that operant performance and the effect of cocaine on this behavior is differentially influenced by genetic make-up.

Animals↗

PubMed1983

Discriminating between reward and performance: a critical review of intracranial self-stimulation methodology.

Despite numerous pharmacological investigations of intracranial self-stimulation (ICSS), the substrates of this behavior have yet to be completely understood. In view of the likelihood that inadequate methodology has hindered the quest for these substrates, the present review was undertaken. Criteria for ICSS methodology should include not only the ability to discriminate reward from gross performance deficit, but also adequate capacity (ability to generate experimental data at a reasonable rate). For numerous reasons, bar-pressing on a continuous reinforcement schedule fails the first criterion despite its ease and rapidity. The use of partial reinforcement schedules may alleviate some of these shortcomings. Analysis of drug-induced response decrement patterns can discriminate gross motoric incapacity from other variables, although the question of subtle response maintenance deficits remains to be answered. Measurements of response rates using alternative operants do not differentiate reward and performance adequately. More promising, "rate-free" measures using locomotion as an operant include the two-platform method of Valenstein and the "locus of rise" method. Comparison of drug effects on ICSS with those on alternate tasks are fraught with pitfalls including the problems of assuring equivalent rates and patterns of responding. The use of differential electrode placements is ideally suited for neurochemically well-characterized drugs, particularly if "double dissociations" can be established during studies of multiple placements. Presentation of different current intensities or frequencies permits the compilation of rate-intensity functions, and drug-induced shifts in these functions have considerable analytical power. Self-regulation of current intensity constitutes a powerful tool that has yet to realize its full potential in the pharmacological study of ICSS. Extensive studies involving self-regulation of stimulation duration ("shuttlebox" studies) suggest that this method may be highly versatile despite several practical difficulties. It is concluded that at least six of these methods appear to do a reasonable job of excluding gross performance deficit. However, the possible influences of other factors, such as subtle response maintenance deficit, incentive or arousal, remain to be resolved in view of the multifactorial nature of ICSS. Multiple tests for ICSS drug or lesion studies are advocated whenever feasible, as no single test appears capable of resolving all theoretical complexities.

Animals↗

PubMed1991

Behavioral economic analysis of activity choice in obese children.

Evaluated children's choice for sedentary versus vigorous activity. Experiment 1 assessed the influence of percent overweight (less than 20%, 20% to 80%, greater than 80%) on choice of a moderately liked vigorous activity at a constant variable ratio (VR) 2 reinforcement schedule versus a highly liked sedentary activity with the schedule varied from VR2 to VR32. All children chose the sedentary choice when the schedules were VR2. As the cost for sedentary activity increased, lean and moderately obese children switched to the vigorous activity, but the very obese children still chose the sedentary activity. Experiment 2 compared moderately obese children's choice between easily accessible, highly or least liked vigorous activities (VR2) and highly liked sedentary activity with the schedule varied from VR2 through VR16. When the reinforcement schedules were equal, and sedentary activity and vigorous activity were rated as equally linked, children chose the sedentary activity. All subjects switched from the sedentary to the vigorous activity, but there were no differences in choice as a function of liking for vigorous activities.

Child↗

PubMed1970

Choice for periodic schedules of reinforcement.

Pigeons' responses in the presence of two concurrently available (initial-link) stimuli produced one of two different (terminal-link) stimuli according to identical but independent variable-interval schedules. Responding in the mutually exclusive terminal links was reinforced with food according to fixed-ratio schedules for six pigeons and according to fixed-interval schedules for two pigeons. None of the pigeons matched the proportion of (choice) responses in the initial links to the proportion of the rates of reinforcement obtained during the terminal links. Instead, as the values of each of the terminal-link schedules were increased by a constant amount, the choice proportions for the stimulus associated with the smaller of the two values increased, even though the relative rates of reinforcement during the terminal links decreased. These results are incompatible with those from previous studies with aperiodic (variable-interval or variable-ratio) schedules. The present results do suggest, however, that in transforming aperiodic schedules into their periodic equivalents, it may be necessary to consider the size of the smallest interreinforcement interval comprising the terminal-link schedules.

Journal Article↗

PubMed1971

Changeover behavior under pairs of fixed-ratio and variable-ratio schedules of reinforcement.

Three pigeons were studied under a pair of equal fixed-ratio schedules and a pair of equal variable-ratio schedules. Each pair was arranged as independent, concurrent schedules and also in a non-independent relation where each peck in a schedule counted toward the response requirement of both schedules. The non-independent pair of variable-ratio schedules maintained much higher changeover rates than any of the other three arrangements. Thus, two factors seemed necessary for generating high changeover rates. Responding on a schedule had to count toward the response requirement of both schedules, and the component schedules had to be variable. These data are consistent with the hypothesis that changeovers are at least partly controlled by the probability of reinforcement following a changeover.

Journal Article↗

PubMed1968

Reversal of preference under progressive-ratio schedules by punishment.

A progressive-ratio reinforcement schedule, in which successive reinforcements required an additional 50 responses, was programmed on one key. A response on a second key reset the progressive-ratio schedule to the first step. Before punishment, all pigeons consistently reset the schedule after reinforcement on the first step, thereby minimizing the number of responses required for reinforcement. Punishment was a brief electric shock contingent upon each response on the reset key. The first effect of punishment was to change the frequency of extra responses on the reset key. Under higher intensities of punishment, the pigeons completed the advanced steps of the progressive-ratio schedule before resetting to the first step. Completions of advanced steps were accompanied by decreases in the overall rate of responding and the rate of reinforcement. When the punishment contingency was removed, the major features of pre-punishment performance were recovered.

Animals↗

PubMed2002

Operant conditioning.

Operant behavior is behavior "controlled" by its consequences. In practice, operant conditioning is the study of reversible behavior maintained by reinforcement schedules. We review empirical studies and theoretical approaches to two large classes of operant behavior: interval timing and choice. We discuss cognitive versus behavioral approaches to timing, the "gap" experiment and its implications, proportional timing and Weber's law, temporal dynamics and linear waiting, and the problem of simple chain-interval schedules. We review the long history of research on operant choice: the matching law, its extensions and problems, concurrent chain schedules, and self-control. We point out how linear waiting may be involved in timing, choice, and reinforcement schedules generally. There are prospects for a unified approach to all these areas.

Attention↗

PubMed1997

Partial reinforcement in appetitive Pavlovian conditioning with rats.

Four experiments examined the effects of a partial reinforcement schedule on extinction using appetitive Pavlovian conditioning. Extinction was slower after partial than after continuous reinforcement when the schedules were administered to different groups (Experiment 1). The opposite result was found in Experiments 2 and 3 when both schedules were presented to the same group in the same context. When the schedules were presented to the same group in different contexts, then extinction was again slower after partial reinforcement (Experiment 3). Experiment 4 demonstrated that a change of context facilitates extinction to a greater extent after conditioning with a partial reinforcement schedule than with a continuous one. The results are explained by assuming that the nonreinforced trials of a partial reinforcement schedule create an internal state that serves as a contextual cue.

Analysis of Variance↗

PubMed1975

Preference and discrimination between response-dependent and response-independent schedules of reinforcement.

Four Asian quail (Coturnix coturnix japonica) were exposed to concurrent-chain schedules, the terminal links of which were either variable-interval 30 sec and variable-time 30 sec, or fixed-interval 30 sec and fixed-time 30 sec. Except for one bird that exhibited a preference for the variable-interval schedule over the variable-time schedule, no consistent preferences were demonstrated for response-dependent or response-independent schedules. However, response rates were three times greater on response-dependent than on response-independent schedules. The discrimination between terminal-link schedules was rapidly recovered after the schedule positions were reversed. Casual observations revealed that the birds engaged in stereotypic circling and pecking while the response-independent schedules were operative.

Journal Article↗

PubMed1971

Effects of cycle length on performance on a temporally defined avoidance schedule.

Three rats were trained on a temporally defined avoidance schedule logically similar to a fixed-interval, limited-hold positive reinforcement schedule. This avoidance schedule was composed of time periods during which responses had no scheduled consequences alternating with time periods during which a response precluded shock. As with fixed-interval length and response rate on positive reinforcement schedules, an inverse relationship was obtained between the length of the no-consequence interval and response rate during the no-consequence interval. An inverse relationship was also obtained between the length of the no-consequence interval and the per cent of shocks avoided. A rate increase within the no-consequence interval, similar to that typically produced by fixed-interval positive reinforcement procedures, was displayed by one of the rats where the no-consequence interval was at intermediate values and frequency of shock was relatively high. The introduction of a discriminative stimulus correlated with the avoidance interval produced typical discriminated avoidance behavior as well as alterations in temporal patterning of responses during the no-consequence interval in the two rats exposed to this procedure. These alterations in temporal patterning disappeared when the discriminative stimulus was removed. The results were consonant with those reported in the literature involving food reinforcement and fixed-interval, limited-hold schedules.

Journal Article↗