Synthesizing concurrent interval performances

Concurrent schedules may be viewed as consisting of two pairs of stay and switch schedules, each pair associated with one of the alternatives. A stay schedule arranges reinforcers for staying and responding at one alternative, whereas the associated switch schedule arranges reinforcers for switching to the other alternative. In standard concurrent schedules, the stay schedule at each alternative is equivalent to the switch schedule at the other alternative. MacDonall (1999) exposed rats to one pair of stay and switch variable-ratio schedules and varied the response requirements across conditions. Combining results from symmetric pairs produced composite performances that were described by the generalized matching law. This outcome was noteworthy because the data were obtained from performances at two alternatives with contingencies that were functionally unrelated to each other. This result suggests that concurrent performances may consist of two unrelated performances that alternate as behavior moves between alternatives. The purpose of the present experiment was to extend those results to interval schedules. Rats were exposed to pairs of random-interval schedules, and across conditions their mean intervals were varied. When data from appropriately paired conditions were combined, the composite performances were consistent with the generalized matching law. In addition, the results supported two models of concurrent performances that were based on local variables at an alternative (behavior, and stay and switch reinforcers): a modified version of the contingency discrimination model (Davison & Jenkins, 1985) and the local model (MacDonall, 1999).     

A note on latent trait theory and Bowker's test

Bowker's test for marginal equality in contingency tables provides a familiar chi-square test to determine whether the marginal distributions are the same across two or more factors or occasions. In this note it is shown how latent trait theory provides a theoretical framework for the development and application of this test.The research reported here was supported by a grant to the senior author from the National Institute on Aging (AG03164).     

A ROLE FOR NEGATIVE REINFORCEMENT OF RESPONSE OMISSION IN PUNISHMENT?

This experiment attempted to disentangle response-rate reductions controlled by the direct suppressive effects of a punisher from those due to negative reinforcement of response omission. Key-peck responding of pigeons was maintained by a conjoint variable-interval 3-min schedule of food presentation variable-interval 30-s schedule of response-dependent electric shock presentation. Omission of responses for 5, 10, or 30 s resulted in the possibility of canceling a scheduled shock. Response rates were a function of required pause duration, with lower rates occurring when longer periods of response omission were required for shock cancellation. These results show that, with several parameters of punishment held constant, response rates were controlled by the negative reinforcement contingency. Such a finding argues for renewed consideration of the role of negative reinforcement in punishment contingencies.     

Loglinear Rasch model tests

Existing statistical tests for the fit of the Rasch model have been criticized, because they are only sensitive to specific violations of its assumptions. Contingency table methods using loglinear models have been used to test various psychometric models. In this paper, the assumptions of the Rasch model are discussed and the Rasch model is reformulated as a quasi-independence model. The model is a quasi-loglinear model for the incomplete subgroup × score × item 1 × item 2 × ... × itemk contingency table. Using ordinary contingency table methods the Rasch model can be tested generally or against less restrictive quasi-loglinear models to investigate specific violations of its assumptions.     

CONTINGENCY MANAGEMENT INTERVENTIONS: EFFECTS ON TREATMENT OUTCOME DURING METHADONE DETOXIFICATION

We examined the effectiveness of a contingency management program in preventing relapse to illicit opiate use and increasing treatment retention during outpatient methadone detoxification treatment. Twenty male opiate addicts were randomly assigned to an experimental or control group. Following a 3-week methadone stabilization period, men in both groups received identical gradual methadone dose reductions during Weeks 4 through 9 and were maintained on placebo during Weeks 10 through 13. Beginning in Week 4, control patients received $5.00 for providing a specimen twice weekly. Experimental patients received $10.00 and a take home methadone dose for each opiate-free urine specimen but forfeited the incentives and participated in more intensive clinic procedures when specimens were opiate positive. The contingency management procedure slowed the rate of relapse to illicit opiate use. Experimental patients provided significantly more opiate-free urines during the methadone dose reduction in Weeks 4 through 9 than control patients, although the difference between groups was no longer significant during placebo administration in Weeks 10 through 13. In addition, the contingency management program improved treatment retention and reduced symptom complaints during the detoxification. The usefulness and limitations of contingency management procedures for outpatient methadone detoxification are discussed.     

CONTINGENCY IN PHYSICS AND COSMOLOGY: A CRITIQUE OF THE THEOLOGY OF WOLFHART PANNENBERG

Abstract. The concept of contingency serves to bridge the doctrine of creation and natural science in Wolfhart Pannenberg's theology. My paper first analyzes the relation of creatio ex nihilo and creatio continua. Next I suggest three categories of contingency: global, local, and nomological. Under each category I assess Pannenberg's use of physics, cosmology, and philosophy of science. Although I agree with Pannenberg's emphasis on continuous creation and on the role of science in renewing the doctrine of creation, I argue for a shift in the discussion from Pannenberg's topics to others, such as the anthropic principle, quantum physics, and thermodynamics.     

Sizing Things Up: Colloquial Reflection as Practical Wisdom

This essay reintroduces Rhetoric as the principle art for giving emphasis and importance to contested matters; in other words, for making things matter. In a speculative reading of the Aristotelian rhetorical tradition, Aristotle's interpretations of magnitude, contengency and practical wisdom are critically examined from both an aesthetic and an ethical-political point of view. The concluding discussion attempts to apply these same concepts to a growing dilemma in the present age. The dilemma is that monumental changes in scale have all but eroded the prospects for engaged encounters with contemporary contingency. It remains the challenge of rhetorical practice to reframe actions and events so that they and we may hold some hope for an engaged civic life.     

The effects of a cooperation contingency on behavior in a continuous three-person environment

Five groups of three subjects resided for 10 or 15 days within a continuously programmed environment. Subjects followed a programmatic arrangement of required and optional private and social activities that determined the individual and group baseline behaviors into which experimental operations were introduced and withdrawn. A cooperation condition was in effect when all three subjects were required to select simultaneous access to a group area before it became available for use. A noncooperation condition was in effect when access to a group area could be selected by individual subjects, without regard to the other subjects' selections. For all groups, the effects of these two conditions on individual and group behaviors were investigated in reversal designs where several successive days occurred under each condition. Groups 1, 4, and 5 had the noncooperation condition interposed between cooperation conditions. Groups 2 and 3 had the cooperation condition interposed between noncooperation conditions. Durations of triadic activities, per cent of time in triadic activities, intercom use, and intersubject program synchronization were greater during cooperation conditions than during noncooperation conditions. These data show that a cooperation contingency within the behavioral program affected both social behavior and the collateral individual behavior necessary to execute the cooperation response.