The temporal selectivity of additive factor effects on the reaction process revealed in ERP component latencies

An experiment was conducted to relate individual components of the event-related brain potential to specific stages of information processing in a two-choice reaction time (RT) task in a group of undergraduate students. Specifically, the latency of the P300 component and the lateralized readiness potential (LRP) were studied as a function of variations in stimulus degradation and response complexity. It was hypothesized that degrading the stimulus would delay the P300 and LRP to the same extent as RT, and that increasing response complexity would affect RT but not P300 latency. The extant literature did not permit any hypothesis regarding the effect of response complexity on LRP latency. The two task variables were found to have additive effects on RT. As predicted, variations in stimulus degradation influenced the latencies of both components, whereas alterations in response complexity had no effect on P300 latency. A significant new finding was that the onset latency of the LRP remained unchanged across levels of response complexity. The overall pattern of results supports the notion of temporal selectivity of stage manipulations that is derived from discrete stage models of human information processing. Furthermore, these results refine the functional interpretation of the LRP by indicating that within the conceptual framework of a stage model the processes this component indexes succeed the start of response choice but precede the start of motor programming.     

Obsessive intrusive thoughts in nonclinical subjects. Part I. Content and relation with depressive, anxious and obsessional symptoms

The present study reports on the development and preliminary validation of a 52 item self-report instrument designed to assess intrusive thoughts, images and impulses that are similar to the aggressive, sexual and disease-related thinking characteristic of clinical obsessions. Two hundred and ninety-three students completed the Obsessive Intrusions Inventory (OII) as well as standard self-report measures of negative cognitions and obsessive, anxious and depressive symptoms. Regression analysis revealed that intrusive thinking was a significant and unique predictor of obsessional but not anxious or depressive symptoms. Furthermore, intrusive thinking showed a moderate correlation with anxious but not depressive cognitions. The results indicate that the intrusive thoughts assessed by the OII are distinct from other forms of negative thinking and may, in fact, constitute an analogue form of clinical obsessions in nonclinical populations.     

The effect of social support on prenatal care.

This article examines the effects of social support on the receipt of adequate prenatal care. A study was conducted to test the hypotheses that social support helps women overcome obstacles to obtaining such care, and that social support has greater effects on women facing the most obstacles. Survey data were gathered for more than 90% of the women who gave birth in Oklahoma hospitals during specific periods in the summer of 1986. The authors found only weak support for the first hypothesis, and for the second hypothesis found only support that must be qualified according to the measure of social support. Strong evidence indicates, however, that difficulty in paying for prenatal care, personal inconveniences, and unwanted pregnancies are obstacles to obtaining such care. The findings account for some of the frequently observed demographic differences associated with receipt of adequate prenatal care, although such differences persisted even after the obstacles were considered. The authors present implications for policy makers seeking to improve women's receipt of adequate prenatal care.     

Social Perceptions of Termination of Medical Treatment: Suicide or Rational Decision?

In two studies, college students read about a critically ill patient who died after CPR attempts failed, CPR was not attempted pursuant to a "Do-Not-Resuscitate" (DNR) order, he terminated all medical treatment, or he self-administered a lethal injection. Death resulting from treatment termination was perceived as significantly more unconventional than were death by CPR failure or DNR order. Ending treatment and lethal injection were perceived as equivalent acts of suicide, and resulted in the patient's being seen as less rational and less capable of making health care decisions. Timing of the patient's decisions regarding treatment, as indicated by the presence or absence of Living Will information, did not alter these perceptions. Results are discussed in light of opposing hypotheses regarding views of "naive" social perceivers toward actions with identical outcomes: that acts of commission are perceived as causal and rated more negatively than acts of omission (Spranca, Minsk, & Baron, 1991), and that acts seen as abnormal are attributed greater causal impact (Hilton & Slugoski, 1986).     

The Importance of Attitudes in the Prediction of College Students' Intentions to Drink

Fishbein's (1967, 1980) theory of reasoned action was used to test the relative importance of attitudes and subjective norms in predicting undergraduate students' intentions to perform 3 different types of social drinking actions: avoiding drinking, drinking enough to get a slight buzz, and drinking enough to get drunk. A multiple regression paradigm was used to determine the relative effectiveness of attitudes and subjective norms in predicting intentions to perform each of the 3 drinking behaviors. Although attitudes were consistently found to be better predictors of intentions than were subjective norms, the strength of the attitude-intention relation varied widely across the 3 actions. In particular, the attitude-intention correlation was strongest for "drinking enough to get drunk." Findings also suggest that subjective norms, previous behavior, and perceived behavioral control are not important variables for predicting this behavior.     

AN EXPERIMENTAL COMPARISON OF THREE DIFFERENT SCHEDULES OF REINFORCEMENT OF DRUG ABSTINENCE USING CIGARETTE SMOKING AS AN EXEMPLAR

The efficacy of three different schedules of reinforcement for promoting and sustaining drug abstinence was compared in this study. Cigarette smoking was studied as an exemplar of stimulant drug self-administration. Sixty cigarette smokers were assigned to one of three groups (progressive rate of reinforcement, fixed rate of reinforcement, and yoked control). Participants in all three groups were asked to refrain from smoking for 1 week. Participants in the progressive and fixed groups achieved greater mean levels of abstinence than those in the control group. Participants in the progressive group were significantly less likely to resume smoking when they became abstinent than participants in the other groups.