Fixed-interval schedules of intravenous cocaine presentation in rats

Fixed-interval schedules of intravenous cocaine presentation were examined as a function of injection dose (0.32 to 0.64 mg/kg) and interval duration (200 to 400 sec) in two rats. Cocaine was found to exert a dose-related temporal control over the initiation of responding that was unaffected by the fixed-interval contingency. Fixed-interval pause duration was linearly related to injection dose and was the same duration as the interresponse time found on continuous reinforcement schedules of cocaine presentation. The fixed-interval pause remained constant with changes in interval duration. Characteristic fixed-interval patterns of responding were observed. However, overall response rates were inversely related to injection dose and directly related to interval duration. Running response rates varied unsystematically with both variables. These findings are at variance with results typically found in studies of fixed-interval food and electric shock presentation.     

Logical and memory processes in a unidimensional concept identification task by children and adults

Behavior of 12-year-old children and of adults was studied in a unidimensional concept identification task. Data have been analyzed within the framework of a hypothesis testing model involving a testing process and a memory process. The data show that testing strategy, as it is described in the model, is very close in children and adults. In children, however, who exhibit lesser retention of information preceding the last trial, the memory process suffers from more limitations than in adults.     

Aspects of language pragmatics and the social perception of lying

Two experiments were conducted in order to examine the influence of linguistic and extralinguistic variables on the attribution of lying. In the first experiment, one of two tape recordings of a target person, who responded either true or false to a list of adjectives, was evaluated by 83 subjects. The subjects' task was to attempt to discover when the target person was not telling the truth. The stimulus tapes were constructed such that the time between the adjective and the target person's response was systematically varied and the adjectives varied on the likability of a person possessing that trait. Overall, it was found that if the target person responded either too quickly or too slowly the subjects attributed his response as a lie more often than if the delay was more intermediate in duration (p<0.01). The adjective likability value in combination with the true or false response of the target person also contributed to the attribution of lying (p<0.01). In the second experiment, the adjectives were rescaled on another dimension thought to influence the attribution of lying: the degree to which the adjective is true of the general population. The results suggest that this new scale is related to the degree to which lie attributions are made.This research was supported in part by the National Institute of Child Health and Human Development under Research Grant 1 P01 HD-01762-01 and the National Institute of Mental Health under Research Grant MN 08260.     

Chinese are more loss averse than British

This research investigates how culture might influence loss aversion. Chinese were expected to be more loss averse than British because of cultural differences in regulatory focus. Study 1 reveals that compared with British participants, Chinese participants were less likely to give up gifts they had received in exchange for new gifts. In Study 2, Chinese and British participants imagined buying a computer which either had a high specification and a high price tag (high reference), or a basic specification and a low price tag (low reference). Participants were informed that the (reference) computer was unavailable, and they had to choose between two available computers, which were both cheaper and less powerful than the high reference computer, and more expensive and more powerful than the low reference computer. The results reveal that the difference in price tag between the two available computers had a bigger impact on Chinese buying decisions than on British buying decisions when it was viewed as a loss. Furthermore, both promotion focus and prevention focus mediated the influence of culture on buying decisions in the low reference condition. No cross‐cultural difference was found in the high reference condition.     

The Co-Development of Parenting Stress and Childhood Internalizing and Externalizing Problems

Although the detrimental influence of parenting stress on child problem behavior is well established, it remains unknown how these constructs affect each other over time. In accordance with a transactional model, this study investigates how the development of internalizing and externalizing problems is related to the development of parenting stress in children aged 4–9. Mothers of 1582 children participated in three one-year interval data waves. Internalizing and externalizing problems as well as parenting stress were assessed by maternal self-report. Interrelated development of parenting with internalizing and externalizing problems was examined using Latent Growth Modeling. Directionality of effects was further investigated by using cross-lagged models. Parenting stress and externalizing problems showed a decrease over time, whereas internalizing problems remained stable. Initial levels of parenting stress were related to initial levels of both internalizing and externalizing problems. Decreases in parenting stress were related to larger decreases in externalizing problems and to the (stable) course of internalizing problems. Some evidence for reciprocity was found such that externalizing problems were associated with parenting stress and vice versa over time, specifically for boys. Our findings support the transactional model in explaining psychopathology.