Carlos R. X. Cançado

Resurgence of temporal patterns of responding

The resurgence of temporal patterns of key pecking by pigeons was investigated in two experiments. In Experiment 1, positively accelerated and linear patterns of responding were established on one key under a discrete-trial multiple fixed-interval variable-interval schedule. Subsequently, only responses on a second key produced reinforcers according to a variable-interval schedule. When reinforcement on the second key was discontinued, positively accelerated and linear response patterns resurged on the first key, in the presence of the stimuli previously correlated with the fixed- and variable-interval schedules, respectively. In Experiment 2, resurgence was assessed after temporal patterns were directly reinforced. Initially, responding was reinforced if it approximated an algorithm-defined temporal pattern during trials. Subsequently, reinforcement depended on pausing during trials and, when it was discontinued, resurgence of previously reinforced patterns occurred for each pigeon and for 2 of 3 pigeons during a replication. The results of both experiments demonstrate the resurgence of temporally organized responding and replicate and extend previous findings on resurgence of discrete responses and spatial response sequences.

Resistance to change and resurgence in humans engaging in a computer task.

The relation between persistence, as measured by resistance to change, and resurgence has been examined with nonhuman animals but not systematically with humans. The present study examined persistence and resurgence with undergraduate students engaging in a computer task for points exchangeable for money. In Phase 1, a target response was maintained on a multiple variable-interval (VI) 15-s (Rich) VI 60-s (Lean) schedule of reinforcement. In Phase 2, the target response was extinguished while an alternative response was reinforced at equal rates in both schedule components. In Phase 3, the target and the alternative responses were extinguished. In an additional test of persistence (Phase 4), target responding was reestablished as in Phase 1 and then disrupted by access to videos in both schedule components. In Phases 2 and 4, target responding was more persistent in the Rich than in the Lean component. Also, resurgence generally was greater in the Rich than in the Lean component in Phase 3. The present findings with humans extend the generality of those obtained with nonhuman animals showing that higher reinforcement rates produce both greater persistence and resurgence, and suggest that common processes underlie response persistence and relapse.

Response elimination, reinforcement rate and resurgence of operant behavior

The effects of reinforcement rate of alternative responding on resurgence were studied in six experiments with pigeons. In Experiment 1A, key pecking was maintained on a multiple variable-interval (VI) VI schedule in the Training phase. In the Response-Elimination phase, a variable differential-reinforcement-of-other-behavior (DRO) schedule was in effect in each component. Reinforcement rates were equal and then, higher in one (rich) component, and lower in the other (lean), than in the Training phase. More resurgence occurred in the lean component, but this could have resulted from response-rate differences between components in the Training-phase. Experiment 1B was a replication of Experiment 1A, but with experimentally-naïve pigeons. Response-Elimination phase reinforcement rates were manipulated systematically in subsequent experiments: In Experiment 2, reinforcement rate was equal, in one component, and lower or higher in the other, than in the Training phase. In Experiment 3, reinforcers were discontinued before differential reinforcement rates were effected. In Experiment 4, reinforcement rates first were differential and, then, equal to those in the Training phase. In Experiments 5 and 6, differential reinforcement rates were arranged by using fixed-DROs and VIs for pecking a different key, respectively. Even though resurgence was not obtained with every pigeon, at least some small-magnitude resurgence occurred in each experiment and was not related systematically to reinforcement rates of alternative responding. Schedule differences, response topography, order of conditions and the length of each phase were not sufficient to account for these results.

Resurgence in Siamese fighting fish, Betta splendens

Resurgence of previously reinforced responding was investigated in male Siamese fighting fish (Betta splendens). Swimming through a ring produced 15-s mirror presentations according to, with different fish, either a fixed-ratio 1 or a variable-interval 60-s schedule of reinforcement. When responding was stable, a differential-reinforcement-of-other-behavior schedule was substituted for the mirror-presentation schedule. Following this, mirror presentations were discontinued (extinction). During this latter phase, there were transient increases in the ring-swim response relative to the frequency of such responding during the differential-reinforcement-of-other behavior schedule. Resurgence was similar for the fish exposed previously to the fixed-ratio or to the variable-interval schedule. These results extend to Siamese fighting fish a well-established behavioral phenomenon previously not observed in this species or with this response topography, and only rarely reported following the removal of a non-consumable reinforcer.

Reversal learning and resurgence of operant behavior in zebrafish (Danio rerio)

Zebrafish are used extensively as vertebrate animal models in biomedical research for having such features as a fully sequenced genome and transparent embryo. Yet, operant-conditioning studies with this species are scarce. The present study investigated reversal learning and resurgence of operant behavior in zebrafish. A target response (approaching a sensor) was reinforced in Phase 1. In Phase 2, the target response was extinguished while reinforcing an alternative response (approaching a different sensor). In Phase 3, extinction was in effect for the target and alternative responses. Reversal learning was demonstrated when responding tracked contingency changes between Phases 1 and 2. Moreover, resurgence occurred in 10 of 13 fish in Phase 3: Target response rates increased transiently and exceeded rates of an unreinforced control response. The present study provides the first evidence with zebrafish supporting reversal learning between discrete operant responses and a laboratory model of relapse. These findings open the possibility to assessing genetic influences of operant behavior generally and in models of relapse (e.g., resurgence, renewal, reinstatement).

Operant models of relapse in zebrafish (Danio rerio): Resurgence, renewal, and reinstatement

Zebrafish are a widely used animal model in biomedical research, as an alternative to mammals, for having features such as a fully sequenced genome, high fecundity, and low-cost maintenance, but behavioral research with these fish remains scarce. The present study investigated whether zebrafish could be a new animal model for studies on the relapse of behavior (e.g., addiction and overeating) after the behavior has been extinguished. Specifically, we examined whether zebrafish would show three different types of relapse commonly studied with other species: resurgence, renewal, and reinstatement. For resurgence, a target response (i.e., approaching a sensor) was established by presenting a reinforcer (i.e., shrimp eggs) contingent upon the response in Phase 1; the target response was extinguished while introducing reinforcement for an alternative response in Phase 2; neither response produced the reinforcer in Phase 3. For renewal, a target response was established under Context A in Phase 1 and was extinguished under Context B in Phase 2; the fish were placed back in Context A in Phase 3, where extinction remained in effect. For reinstatement, a target response was established in Phase 1 and was extinguished in Phase 2; the reinforcer was presented independently of responding in Phase 3. Each type of relapse occurred in Phase 3. These results replicate and extend previous findings on relapse to a new species and suggest that zebrafish can be a useful animal model for studying the interactions of biological and environmental factors that lead to relapse.

The recurrence of negatively reinforced responding of humans

The recurrence of negatively reinforced responding of humans was studied in three experiments. In each experiment during Baseline, key-pressing produced 3-s timeouts from a requirement to exert finger pressure on a force cell according to variable- or fixed-ratio schedules of reinforcement. In Experiment 1, resurgence was studied by arranging a differential-reinforcement-of-other-behavior schedule in the second phase, and extinction in the Test phase. In Experiment 2, ABA renewal was studied by extinguishing responding in the second phase in a different context and, in the Test phase, by presenting the Baseline-phase context when extinction still was in effect. In Experiment 3, reinstatement was studied by arranging extinction in the second phase, followed by the delivery of response-independent timeouts in the Test phase. Resurgence and renewal occurred consistently for each participant in Experiments 1 and 2, respectively. In Experiment 3, reinstatement was observed less consistently in four participants. The results of these experiments replicate and extend to negatively reinforced responding previous findings of the resurgence and renewal of positively reinforced responding obtained mainly with nonhuman animals.

COMBINATIONS OF RESPONSE-REINFORCER RELATIONS IN PERIODIC AND APERIODIC SCHEDULES†‡

Key pecking of 4 pigeons was studied under a two-component multiple schedule in which food deliveries were arranged according to a fixed and a variable interfood interval. The percentage of response-dependent food in each component was varied, first in ascending (0, 10, 30, 70 and 100%) and then in descending orders, in successive conditions. The change in response rates was positively related to the percentage of response-dependent food in each schedule component. Across conditions, positively accelerated and linear patterns of responding occurred consistently in the fixed and variable components, respectively. These results suggest that the response-food dependency determines response rates in periodic and aperiodic schedules, and that the temporal distribution of food determines response patterns independently of the response-food dependency. Running rates, but not postfood pauses, also were positively related to the percentage of dependent food in each condition, in both fixed and variable components. Thus, the relation between overall response rate and the percentage of dependent food was mediated by responding that occurred after postfood pausing. The findings together extend previous studies wherein the dependency was either always present or absent, and increase the generality of the effects of variations in the response-food dependency from aperiodic to periodic schedules.

Efeitos do reforçador empregado em história de reforço recente e remota

Twelve undergraduates in four groups responded by clicking on a button presented on a computer screen. Participants of Groups 1 and 3 were exposed to the sequence FR - DRL - FI and those of Groups 2 and 4 to the sequence DRL - FR - FI. Reinforcers were points exchanged by money (Groups 1 and 2) or points only (Groups 3 and 4). Effects of recent histories over FI performance were consistently observed when points were exchanged by money. DRL histories, recent or remote, affected subsequent performance especially when reinforcers were points only. Results suggest that the reinforcer that is used modulates history effects over FI performance and that its manipulation can clarify some discrepancies between human and non-human in schedules of reinforcement.

Relative effects of reinforcement and punishment on human choice

ABSTRACT An experiment with humans was conducted to assess the relative effects of reinforcement and punishment on choice. Point gains and losses were programmed as reinforcers and punishers, respectively. Participants used a mouse to click two buttons on a computer screen while the ratio of point gains was varied according to a concurrent variable-interval schedule. Responding was sensitive to relative point gains in baselines. When a schedule of point loss was superimposed on one button, relative to baseline, bias away from the point-loss button was observed, indicating the punishment effects of losses. Finally, a schedule arranging equal rates of both point gains and losses was superimposed on one button. One participant showed no change in bias and two showed shifts in bias away from the alternative with the superimposed schedule relative to baseline. These results suggest that punishment effects are at least equal and sometimes greater than reinforcement effects..