Role of conditioned reinforcers in the initiation,maintenance and extinction of drug-seeking behavior

The development of a secondary reinforcer as a result of associating a neutral stimulus (buzzer) with intravenous (IV) doses of morphine was studied in rats. Secondary reinforcement developed in the absence of physical dependence and followed the association of the stimulus with either response-contingent or non-contingent injections of morphine. Strength of the conditioned reinforcer, measured in terms of responding on a lever for the stimulus plus infusion of saline solution, was proportional to the unit dosage of morphine employed in pairings of buzzer and drug. When extinction of the lever-press response for IV morphine was conducted (by substituting saline for morphine solution) in the absence of the conditioned reinforcing stimulus, it was seen later that the stimulus could still elicit lever responses, until it too had been present for a sufficient interval of non-reinforced responding. Similarly, extinction of the response for morphine by blocking its action with naloxone in the absence of the stimulus did not eliminate the conditioned reinforcement. Another study showed that a passive, subcutaneous (SC) dose of morphine served to maintain lever-pressing on a contingency of buzzer plus sahne infusion. Furthermore, the stimuli resulting from the presence of morphine (after a SC injection) were able to reinstate the lever-responding with only the buzzer-saline contingency when such responses had previously been extinguished. Moreover, it was shown thatd-amphetamine could restore responding under the same conditions, and that morphine could also do so for rats in which the primary reinforcer had beend-amphetamine. It is suggested that animal data such as these show that procedures designed for the elimination of human drug-taking behavior must take into account secondary reinforcers as well as the primary reinforcer(s).     

Prior experience as a moderator of disaster impact on anxiety symptoms in older adults

As participants in a panel study, 234 older adults were interviewed before, as well as after, serious flooding occurred in southeastern Kentucky. Floods are not uncommon in this area, but these were more widespread than most, and resulted in both previously exposed and newly exposed subsamples of disaster victims. Flood impact was measured at both personal and community levels. With preflood symptoms controlled, there were modest flood effects on both trait anxiety and weather-specific distress in older adults without prior flood experience, but no flood effects in older adults who had been in floods before. Thus, the study provides support for the "inoculation hypothesis" and other conceptualizations that emphasize the advantage of being familiar or experienced with a stressor that is at hand. An implication is that "experienced" victims could be a valuable resource in prevention efforts.     

Application of model-selection criteria to some problems in multivariate analysis

A review of model-selection criteria is presented, with a view toward showing their similarities. It is suggested that some problems treated by sequences of hypothesis tests may be more expeditiously treated by the application of model-selection criteria. Consideration is given to application of model-selection criteria to some problems of multivariate analysis, especially the clustering of variables, factor analysis and, more generally, describing a complex of variables.     

The Composite-Stimulus Analysis and the Quantal Nature of Stimulus Control: Response and Incentive Factors

The Psychological Record -     

KOHLBERG'S THEORY OF MORAL DEVELOPMENT: CRITICAL ANALYSIS OF VALIDATION STUDIES WITH THE DEFINING ISSUES TEST

This paper evaluates studies that have used the Defining Issues Test for validating Kohlberg's theory of moral stage development. Although this test was introduced to overcome inadequacies with Kohlberg's procedure, it too encounters serious methodological and conceptual difficulties. Its limitations include truncation of the stages and age range assessed. The validation studies, both cross-sectional and longitudinal, have used a correlational design and confounded age with other variables. Threats to internal and external validity obviate support claimed for Kohlberg; moral reasoning thus measured seems a function of education, IQ, direct moral training, and cultural values rather than maturation. Nor is the stage model upheld by longitudinal data, which fail to reveal sequential stepwise change and belie occasional regression. Attempted redefinition of the stage concept to salvage these data has not rescued Kohlberg's proposal, which remains to be validated empirically.