Contingent stimuli signal subsequent reinforcer ratios (original) (raw)
Related papers
Conditional reinforcers and informative stimuli in a constant environment
Journal of the Experimental Analysis of Behavior, 2009
Five pigeons responded on steady-state concurrent variable-interval variable-interval schedules of food presentation in which half of the foods were removed and replaced with nonfood stimuli. Across conditions, the stimuli were either paired or unpaired with food, and the correlation between the ratio of food deliveries on the two alternatives and the ratio of nonfood stimuli was either 21, 0, or +1. Neither the pairing of stimuli with food, nor the correlation between stimuli and food, affected generalized-matching performance, but paired stimuli had a demonstrable effect at a local level of analysis. This effect was independent of the food-stimulus correlation. These results differ from results previously obtained in a frequently changing environment. We attribute this difference in results to differences in the information value of response-contingent stimuli in frequently changing versus relatively constant environments, as well as to differences between forward pairing and simultaneous pairing of the stimuli with food.
Behavioural Processes, 2020
When reinforcer availability on one alternative of a concurrent schedule is signaled by a discriminative stimulus, responding on that alternative decreases. We investigated how the correlation between signal presentation and reinforcement (signal reliability) affects choice between signaled and unsignaled alternatives. Six pigeons responded in a concurrent schedule, in which reinforcers on one alternative were signaled by a key-color change. Across conditions, the probability of reinforcement following signal presentation varied (the probability in its absence was the complement). As signal reliability increased, response rates and latencies following signal onset on the signaled alternative decreased, whereas responding on the unsignaled alternative remained unchanged. Because the signal did not alter overall reinforcer rates, these findings are consistent with matching theories and research suggesting that responding on one alternative of a concurrent schedule depends on reinforcer, but not response, rates on other alternatives. However, these findings are inconsistent with others demonstrating concomitant changes in responding on signaled and unsignaled alternatives. We consider whether a responsecompetition account of concurrent performance can explain these discrepancies, and suggest avenues for future studies to investigate the mechanisms underlying effects of signaled reinforcement in concurrent schedules.
Conditioned reinforcement as a function of the intermittent pairing of a stimulus and a reinforcer
1981
Pigeons' responses were maintained under a multiple schedule of conditioned and unconditioned reinforcement. Responses in the first component produced food according to a randominterval (RI) 90-sec schedule. Each food presentation was preceded by a brief stimulus. In this condition, the ratio of brief-stimulus to food presentations was 1:1, as the brief stimulus was continuously paired with food. In other conditions, responses in the first component also produced the brief stimulus unaccompanied by food, according to an independent RI 90-sec or RI 30-sec schedule. In these conditions, the brief stimulus was intermittently paired with food according to 2:1 and 4:1 ratios, respectively. Responses in the second component produced only the brief stimulus, according to a fixed-ratio schedule. Response rate in the second component was highest when the ratio of brief-stimulus to food presentations in the first component was 1:1, intermediate when the ratio was 2:1, and lowest when the ratio was 4:1, indicating a gradient of conditioned reinforcement strength. These data are consistent with some early experiments that used extinction procedures to test the hypothesis that intermittent pairing of a stimulus and a reinforcer generates a conditioned reinforcer weaker than one produced by continuous pairing.
Examining the Discriminative and Strengthening Effects of Reinforcers in Concurrent Schedules
Journal of the Experimental Analysis of Behavior, 2011
Reinforcers may increase operant responding via a response-strengthening mechanism whereby the probability of the preceding response increases, or via some discriminative process whereby the response more likely to provide subsequent reinforcement becomes, itself, more likely. We tested these two accounts. Six pigeons responded for food reinforcers in a two-alternative switching-key concurrent schedule. Within a session, equal numbers of reinforcers were arranged for responses to each alternative. Those reinforcers strictly alternated between the two alternatives in half the conditions, and were randomly allocated to the alternatives in half the conditions. We also varied, across conditions, the alternative that became available immediately after a reinforcer. Preference after a single reinforcer always favored the immediately available alternative, regardless of the local probability of a reinforcer on that alternative (0 or 1 in the strictly alternating conditions, .5 in the random conditions). Choice then reflected the local reinforcer probabilities, suggesting some discriminative properties of reinforcement. At a more extended level, successive same-alternative reinforcers from an alternative systematically shifted preference towards that alternative, regardless of which alternative was available immediately after a reinforcer. There was no similar shift when successive reinforcers came from alternating sources. These more temporally extended results may suggest a strengthening function of reinforcement, or an enhanced ability to respond appropriately to ''win-stay'' contingencies over ''win-shift'' contingencies.
Journal of the Experimental Analysis of Behavior, 2007
When behavior suggests that the value of a reinforcer depends inversely on the value of the events that precede or follow it, the behavior has been described as a contrast effect. Three major forms of contrast have been studied: incentive contrast, in which a downward (or upward) shift in the magnitude of reinforcement produces a relatively stronger downward (or upward) shift in the vigor of a response; anticipatory contrast, in which a forthcoming improvement in reinforcement results in a relative reduction in consummatory response; and behavioral contrast, in which a decrease in the probability of reinforcement in one component of a multiple schedule results in an increase in responding in an unchanged component of the schedule. Here we discuss a possible fourth kind of contrast that we call within-trial contrast because within a discrete trial, the relative value of an event has an inverse effect on the relative value of the reinforcer that follows. We show that greater effort, longer delay to reinforcement, or the absence of food all result in an increase in the preference for positive discriminative stimuli that follow (relative to less effort, shorter delay, or the presence of food). We further distinguish this within-trial contrast effect from the effects of delay reduction. A general model of this form of contrast is proposed in which the value of a primary or conditioned reinforcer depends on the change in value from the value of the event that precedes it.
Conjunctive schedules of reinforcement II: response requirements and stimulus effects1
Journal of the Experimental Analysis of Behavior, 1975
Responding of three pigeons was maintained under conjunctive fixed-ratio, fixed-interval schedules where a key peck produced food after both schedule requirements were completed. The individual schedule requirements were then successively removed and reinstated with responding maintained under the following conditions: conjunctive fixedratio, fixed-time; fixed-time; and fixed-interval schedules. Patterns of responding changed in accord with the successive removal of the schedule requirements. Compared to the conjunctive fixed-ratio, fixed-interval schedule, pause duration increased and response rate decreased under conjunctive fixed-ratio, fixed-time schedules and under fixed-time schedules alone. Overall mean rates of responding were highest and pause duration lowest under fixed-interval schedules. When changes in the keylight colors were correlated with completion of the fixed-ratio, the end of the fixed-interval, or both of these conditions, the pattern of responding was modified and indicated a greater degree of control by the individual schedules. Although two birds showed large increases in interreinforcement time when they were initially exposed to the conjunctive schedule, when responding stabilized this measure was largely invariant for all birds across most schedule conditions.
The Psychological Record
The purpose of the present experiment was to evaluate which method, stimulus-stimulus pairing or operant discrimination training, establishes neutral stimuli as more effective conditioned reinforcers, and to explore ways to maintain effects of the stimuli established as conditioned reinforcers. Four rats were exposed to an operant discrimination training procedure to establish a left-situated light as a conditioned reinforcer and to a stimulusstimulus pairing procedure to establish a right-situated light as a conditioned reinforcer. Acquisition of new responses was then arranged to determine how formerly neutral stimuli could maintain responding when the unconditioned reinforcer (water) was presented intermittently in an experimental design similar to a concurrent-chain procedure. During this acquisition, two levers were concurrently available and presses on the left lever produced an operant discrimination trial (left light-response-water), whereas presses on the right lever produced a stimulus-stimulus pairing trial (right light-water). The results suggest that the operant discrimination training procedure was more effective in establishing a neutral stimulus as a conditioned reinforcer and also maintained a higher rate of responding over time.
Journal of The Experimental Analysis of Behavior, 1991
The present study measured the effects of stimulus and reinforcer variations on pigeons' behavior in two different choice procedures. Two intensities of white light were presented as the stimuli on the main key in a switching-key concurrent schedule and as the sample stimuli in a signal-detection procedure. Under both procedures, the scheduled rate of reinforcement was varied across conditions to produce various ratios of obtained reinforcement. These ratios were obtained for seven pairs of light intensities. In the concurrent schedules, the effects of reinforcer-ratio variations were positively correlated with the physical disparity between the two light intensities. In the signal-detection procedure, changes in the reinforcer ratio produced greater effects on performance when stimulus disparity was very low or very high compared to those found at intermediate levels of stimulus disparity. This discrepancy creates a dilemma for existing behavioral models of signal-detection performance.
Journal of The Experimental Analysis of Behavior, 2007
Two experiments with pigeons investigated the effects of contingencies between interresponse times (IRTs) and the transitions between the components of 2-and 4-component chained schedules (Experiments 1 and 2, respectively). The probability of component transitions varied directly with the most recent (Lag 0) IRT in some experimental conditions and with the 4th (Lag 4) IRT preceding the most recent one in others. Mean component durations were constant across conditions, so the reinforcing effect of stimulus change was dissociated from that of delay to food. IRTs were longer in the Lag-0 than in the Lag-4 conditions of both experiments, thus demonstrating that stimulus change functioned as a reinforcer. In the Lag-0 conditions of Experiment 2, the Component-1 IRTs increased more than the Component-2 IRTs, which in turn increased more than the Component-3 IRTs. This finding runs counter to the conditioned-positive-reinforcement account of chained-schedule responding, which holds that the reinforcing effect of stimulus change should vary in strength as an inverse function of the delay to the unconditioned reinforcer at the end of the chain because conditioned reinforcement is due to first-or higher-order classical conditioning. Therefore, we present other possible explanations for this effect.