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.     

Rawls and Nozick: Justice without well-being

The Journal of Value Inquiry -     

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.     

Latent Structure of the Sources of Mathematics Self-Efficacy

General social cognitive theory and its career-specific elaborations posit four primary sources through which self-efficacy beliefs are acquired and modified: personal performance accomplishments, vicarious learning, social persuasion, and physiological states and reactions. We present two studies exploring the dimensionality of these sources within the context of career-relevant mathematics activities. In Study 1, 295 college students completed measures of the source variables. Testing two- through five-factor models, we found strongest support for a four-factor latent structure of the efficacy sources. In Study 2, involving 481 high school students, a five-factor model fit the data well. We also found evidence of a higher order factor structure in both samples. Several directions for further research on the sources of efficacy information are considered, along with implications for career and academic interventions.     

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).