The present study investigated the effects of fixed-ratio (FR) and variable-ratio (VR) reinforcement schedules on patterns of cooperative responding in pairs of rats. Experiment 1 arranged FR 1, FR 10, and VR 10 schedules to establish cooperative responding (water delivery depended on the joint responding of two rats). Cooperative response rates and proportions were higher under intermittent schedules than under continuous reinforcement. The FR 10 schedule generated a break-and-run pattern, whereas the VR 10 schedule generated a relatively high and constant rate pattern. Experiment 2 evaluated the effects of parametric manipulations of FR and VR schedules on cooperative responding. Rates and proportions of cooperative responding generally increased between ratio sizes of 1 and 5 but showed no consistent trend as the ratio increased from 5 to 10. Experiment 3 contrasted cooperative responding between an FR6 schedule and a yoked control schedule. Coordinated behavior occurred at a higher rate under the former schedule. The present study showed that external consequences and the schedules under which the delivery of these consequences are based, select patterns of coordinated behavior.

The effects of response-reinforcer relations on coordinated responding were investigated. Coordinated responding was defined as two lever presses, one by each rat that occurred within 500 ms of one another. Four conditions were arranged in an ABCB design. Coordinated responding was reinforced according to a fixed-ratio 6 (FR 6) schedule in Condition A. In Condition B, a response by each rat was required, independent of their temporal proximity, to produce water delivery under a variable-interval schedule. Condition C was a replication of Condition B, except that coordinated responding was required for reinforcer deliveries. All conditions involved simultaneous reinforcement, that is the rats received access to reinforcers at the same time. The results extended previous findings by demonstrating the requirement of coordinated responses to produce reinforcement affected both coordinated response rates and the proportion of such responses relative to the total responses in a session, in that both measures were higher in Conditions A and C than in Condition B. There also was control of the temporal distribution of coordinated responding by the type of schedule (FR or VI): A “break-and-run” pattern was observed under the FR schedule, and a constant response rate was observed under the VI schedule.

Coordinated responses of 5 dyads of rats were investigated under fixed-ratio (FR) schedules of mutual water reinforcement. Coordinated responding was defined as 2 consecutive lever-presses, 1 from each of 2 rats, occurring <.5 s apart. In the FR schedules, each coordinated episode was defined as 1 response in the FR sequence. The size of FR schedules was parametrically manipulated assuming the values of FR 1, 6, 12, 18, 24, 30, 50, and 9, in this order. Each FR remained in effect until responding reached stability. Under all conditions, pairs of rats received access to water simultaneously (mutual reinforcement). Rates and proportions of coordinated responding showed a bitonic inverted U-shaped function of ratio size. Postreinforcement pauses increased systematically as the interreinforcement interval increased. Local rates and proportions increased as a function of response location within ratios. Results of a control condition with relaxed temporal constraints for mutual reinforcement showed decreases in rates and proportion of coordinated responses, suggesting that the coordinated responses were controlled by the mutual reinforcement contingencies. The present experiment showed that coordinated responding is quantitatively affected by 3 properties of FR schedules: response requirement, reinforcement rates, and proximity to reinforcement.

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No procedimento de supressão condicionada um pareamento entre um estímulo neutro e um estímulo aversivo é sobreposto a uma linha de base de comportamento operante. O pareamento resulta em supressão do responder durante o estímulo aversivo condicionado e sua recuperação após a ocorrência do estímulo aversivo incondicionado. Este trabalho teve como objetivo replicar estudo prévio que mostrou que os efeitos supressivos do pareamento ficaram parcialmente sob controle do estímulo discriminativo. Diferentemente do estudo anterior, a presente pesquisa utilizou contrabalanceamento do componente pareado entre sujeitos. Foi empregada uma linha de base de esquemas múltiplos de intervalos variáveis (mult VI VI) iguais, correlacionados com a presença ou a ausência de luz (componente claro/escuro). O procedimento seguiu um delineamento de reversão ABAC, em que A era a linha de base, o pareamento tom-choque foi introduzido somente em um dos componentes em B e em C o tom era apresentado sem o choque (extinção do pareamento). Observou-se supressão nas taxas totais de respostas em ambos os componentes na Condição B (efeito generalizado), porém, com efeito mais acentuado no componente com paramento (efeito discriminativo). Além disso, uma análise das taxas locais replicou os achados prévios: a supressão foi mais acentuada entre o início do estímulo de aviso e o término do choque. Os resultados não apontam conclusivamente para uma diminuição nas taxas globais de respostas nas fases finais (A e C). Os efeitos de generalização podem ter sido parcialmente favorecidos pelo contexto (o mesmo para os dois componentes), o que deverá ser melhor investigado.Palavras-Chave: Esquemas múltiplos, intervalo variável, controle aversivo, supressão condicionada, ratos.