Patterns of maternal responding in postpartum mothers with schizophrenia

Little is known about how schizophrenia might affect how a mother responds to her infant, such as whether responding is reduced or impaired. The aim was to identify, from brief videotaped interactions, whether the responses of mothers with schizophrenia were fewer, less positive, more negative, and more ‘abnormal’ than mothers with affective disorder, and whether their infants (mean age: 15 weeks) lacked activity or initiation to which mothers could respond. Mothers with schizophrenia (N = 14) were as responsive as mothers with affective disorder (N = 31), but they showed markedly low positive responsiveness. Only the schizophrenia group exhibited non-responses as a result of being psychologically withdrawn from the interaction, and abnormal behaviors. Inconsistent to our hypothesis, infants in both groups showed similar levels of activity, initiative and negativity. The findings highlight the need for further research to examine the contribution of maternal response impairments to the developmental vulnerability of this genetically high-risk group.     

VOUCHER‐BASED CONTINGENT REINFORCEMENT OF SMOKING ABSTINENCE AMONG METHADONE‐MAINTAINED PATIENTS: A PILOT STUDY

This study evaluated the efficacy of a contingency management (CM) intervention to promote smoking cessation in methadone‐maintained patients. Twenty participants, randomized into contingent (n = 10) or noncontingent (n = 10) experimental conditions, completed the 14‐day study. Abstinence was determined using breath carbon monoxide and urine cotinine levels. Contingent participants received voucher‐based incentives for biochemical evidence of smoking abstinence. Noncontingent participants earned vouchers independent of smoking status. Contingent participants achieved significantly more smoking abstinence and longer durations of continuous smoking abstinence than did noncontingent participants. These results support the potential efficacy of using voucher‐based CM to promote smoking cessation among methadone‐maintained patients.     

Effects of Initial Abstinence and Programmed Lapses on The Relative Reinforcing Effects of Cigarette Smoking

Fifty-eight smokers received abstinence-contingent monetary payments for 1 (n  =  15) or 14 (n  =  43) days. Those who received contingent payments for 14 days also received 0, 1, or 8 experimenter-delivered cigarette puffs on 5 evenings. The relative reinforcing effects of smoking were assessed in a 3-hr session on the final study day, when participants made 20 choices between smoking or money. The reinforcement contingencies exerted robust control over smoking, and programmed smoking lapses produced few discernible effects. These results further illustrate the robust control that reinforcement contingencies can exert over cigarette smoking and suggest that any effects of lapses on the relative reinforcing effects of smoking are modest under conditions involving abstinence-contingent reinforcement contingencies.     

The Relative Contribution of Economic Valence to Contingency Management Efficacy: A Pilot Study

We investigated the extent to which a contingency management (CM) procedure that deducted money from a grand total available at the end of the study compared to a procedure in which money accumulated with continued abstinence from cigarette smoking. Results suggested that the procedure in which money increased contingent on abstinence resulted in a significantly greater likelihood of obtaining a clinically relevant (i.e., 48-hr) period of abstinence. In terms of attendance, participants in the condition in which monetary reinforcement accrued with consecutive instances of abstinence were significantly less likely to miss consecutive appointments than those in which money was deducted for failure to abstain.     

Comparison of components of the Good Behavior Game in a preschool classroom

The Good Behavior Game (GBG) is an effective intervention package for decreasing disruptive behavior in various populations and environments. There is, however, limited research evaluating the GBG with preschoolers. Furthermore, few studies have evaluated the effects of components of the GBG, and of those that have, most have done so only after exposure to the GBG package. We evaluated the effects (a) of the GBG on disruptive behavior of preschoolers during group instruction and (b) the major components of the GBG before and after implementation of the GBG package (c) at both the group and individual level. Results suggest that the GBG package was necessary for decreasing disruptive behavior. However, after exposure to the GBG, a response‐independent contingency was effective for maintaining low levels of disruptive behavior at both the group and individual level.     

Contingency tracking during unsignaled delayed reinforcement: Effects of delay duration and d‐amphetamine

In two experiments, the role of the response–reinforcer relation in maintaining low‐rate responding under unsignaled delay conditions was investigated. In both experiments pecking by pigeons on one response key, denoted the relevant key, was reinforced under an unsignaled delay‐of‐reinforcement procedure (defined as tandem variable‐interval (VI) differential‐reinforcement‐of‐other behavior [DRO] schedule). Responding on a second key, denoted the irrelevant key, had no programmed consequences. Between sessions, the location of the relevant key varied (after one, two, or three sessions) pseudorandomly. In Experiment 1, the delay (DRO) duration was manipulated parametrically. Overall, proportional relevant‐key response rates (relevant‐key response rates / [relevant‐key response rates + irrelevant key response rates]) increased across 3‐session sequences in which the relevant key remained in the same location and decreased as the DRO duration was changed systematically (2, 5, and 10 s). In Experiment 2, acute administration of d‐amphetamine increased proportional relevant‐key response rates during 1‐day sequences for only the DRO 5‐s duration, and results over 3‐day sequences, once a discrimination had already been established, were inconsistent. Results support that the response–reinforcer relation is the primary determinant of responding, and such discriminations are relatively resistant to disruption or potentiation by behaviorally active doses of d‐amphetamine.     

Local effects of delayed food

Five pigeons were trained on a procedure in which seven concurrent variable-interval schedules arranged seven different food-rate ratios in random sequence in each session. Each of these components lasted for 10 response-produced food deliveries, and components were separated by 10-s blackouts. We varied delays to food (signaled by blackout) between the two response alternatives in an experiment with three phases: In Phase 1, the delay on one alternative was 0 s, and the other was varied between 0 and 8 s; in Phase 2, both delays were equal and were varied from 0 to 4 s; in Phase 3, the two delays summed to 8 s, and each was varied from 1 to 7 s. The results showed that increasing delay affected local choice, measured by a pulse in preference, in the same way as decreasing magnitude, but we found also that increasing the delay at the other alternative increased local preference. This result casts doubt on the traditional view that a reinforcer strengthens a response depending only on the reinforcer's value discounted by any response-reinforcer delay. The results suggest that food guides, rather than strengthens, behavior.     

Exploratory analysis of contingency tables by loglinear formulation and generalizations of correspondence analysis

Goodman's (1979, 1981, 1985) loglinear formulation for bi-way contingency tables is extended to tables with or without missing cells and is used for exploratory purposes. A similar formulation is done for three-way tables and generalizations of correspondence analysis are deduced. A generalized version of Goodman's algorithm, based on Newton's elementary unidimensional method is used to estimate the scores in all cases.This research was partially supported by National Science and Engineering Research Council of Canada, Grant No. A8724. The author is grateful to the reviewers and the editor for helpful comments.     

Color preference in pigeons: stimulus intensity and reinforcement contingency effects in the avoidance of blue stimuli.

In a procedure intended to determine color preference in pigeons (which partially replicated Catania, Owens, & von Lossberg, 1983), two keys were illuminated by different colors drawn from a set of amber, red, green, or blue stimuli; this was followed by the presentation of grain when either of the two colors was pecked. The grain was illuminated alternately across trials with the colors presented on the keys. In Experiment 1 the intensity of the color stimuli used was not equalized, whereas in Experiment 2 the intensity of the colors was equalized. The low preference for blue found in Experiment 1, as measured by differential key pecking, was not found in Experiment 2. The discriminability of the intensity-equalized colors was confirmed in Experiment 2a, in which equal-intensity color discrimination problems were presented. In Experiment 3, as in Catania et al. (1983), a response-independent reinforcement schedule was used, but with intensity-equalized colors. In contrast to Experiment 2, very low preference for blue was found here and in Experiment 4, which used a within-subject procedure. These findings suggest that pigeon color preference may be a function of intensity, but all controlling variables have not as yet been identified.