Blood lead (Pb) levels: a potential environmental mechanism explaining the relation between socioeconomic status and cardiovascular reactivity in children.

OBJECTIVE: A number of studies have shown an association between socioeconomic status (SES) and cardiovascular reactivity to acute stress. In addition, the authors recently reported that higher early childhood blood lead (Pb) levels are associated with significantly greater total peripheral (vascular) resistance (TPR) responses to acute stress. It is not known whether the SES-TPR association is mediated by underlying differences in blood lead levels. DESIGN: Participants were 9.5-year-old children (N=122) with established early childhood blood lead levels. MAIN OUTCOME MEASURES: Family SES was measured using the Hollingshead Index, blood lead levels were abstracted from pediatrician and state records, and children's cardiovascular responses to acute stressors were measured in the laboratory with impedance cardiography and an automated blood pressure monitor. RESULTS: Lower family SES was shown to be associated with significantly higher blood lead levels as well as significantly heightened systolic blood pressure, diastolic blood pressure, and TPR responses to acute stress tasks. A mediational analysis confirmed that Pb was a significant mediator of the SES-TPR reactivity association; some evidence also suggested moderation. CONCLUSION: These results suggest the importance of considering the chemical environment as well as social and psychological environment when evaluating cardiovascular effects of low SES.     

Are you looking at me? Measuring the cone of gaze

The processing of gaze cues plays an important role in social interactions, and mutual gaze in particular is relevant for natural as well as video-mediated communications. Mutual gaze occurs when an observer looks at or in the direction of the eyes of another person. The authors chose the metaphor of a cone of gaze to characterize this range of gaze directions that constitutes "looking at" another person. In 4 experiments using either a real person or a virtual head, the authors investigated the influences of observer distance, head orientation, visibility of the eyes, and the presence of a 2nd head on the perceived direction and width of the gaze cone. The direction of the gaze cone was largely affected by all experimental manipulations, whereas its angular width remained comparatively stable.     

Stereokinetic effect and its relation to the kinetic depth effect.

The stereokinetic effect (SKE) has been defined and studied by nested circular patterns rotating on a turntable. Circles must appear not to rotate as they revolve, which in turn results in their appearing to translate relative to one another. A powerful illusion of object depth results even though the individual circles do not undergo an appropriate foreshortening consistent with their apparent changes in slant. It is suggested and tested that the SKE is based on the changing positions between the nested contours despite the absence of any change within each contour, whereas the kinetic depth effect (KDE) entails both kinds of change. It follows that a turntable method of presentation is not necessary, and between-contour transformations can be simulated by computer animation. Displays consisting of simple translations were shown to evoke robust depth impressions as were patterns consisting of contours of varying shapes. Comparisons of the depth, compellingness, and rigidity of matched SKE and KDE displays are reported. The SKE is taken to be paradigmatic for how the visual system perceives depth when observing small object rotations that occur in everyday situations.     

The somatic and vegetative-regulatory behavior of the healthy organism during conditioning of the insulin effect

Symptoms produced by repeated daily injection of insulin (3 units/kg i.v.) in dogs revealed the principle of fractional conditioning: the general behavior and changes in the cortical EEG characteristic of insulin action could become a conditional reflex (evoked by the injection of physiological saline i.v. and a CS)—while the blood sugar level, the heart rate, the EKG, and body temperature did not become CRs. This split illustrates the principle shown by Gantt that centrally-mediated effects of an agent are conditionable while those resulting only from direct peripheral action cannot become CRs. From this principle it may be assumed that the effects of insulin (behavioral, EEG) are mediated through the central nervous system, while other insulin effects (those not conditionable) are a result of peripheral action. Two methods of blood sugar determination (Hagedorn-Jensen and glucose oxidase) in both venous and arterial blood were used in these experiments, and the data resulting from 14,056 determinations were analyzed.     

Effects of task-irrelevant texture motion on time-to-contact judgments

We investigated the effect of local texture motion on time-to-contact (TTC) estimation. In Experiment 1, observers estimated the TTC of a looming disk with a spiral texture pattern in a prediction-motion task. Rotation of the spiral texture in a direction causing illusory contraction resulted in a significant TTC overestimation, relative to a condition without texture rotation. This would be consistent with an intrusion of task-irrelevant local upon task-relevant global information. However, illusory expansion did not cause a relative TTC underestimation but rather also a tendency towards overestimation. In Experiment 2, a vertical cylinder moved on the frontoparallel plane. Observers judged its TTC with a finish line. The cylinder was textured with stripes oriented in parallel to its longitudinal axis. It was either not rotating, rotating such that the stripes moved towards the finish line (i.e., in the same direction as the contour), or rotating such that the stripes moved away from the finish line. Both types of texture motion caused TTC overestimation compared to the static condition. Experiment 3 showed that the different effects of task-relevant and task-irrelevant texture motion are not a mere procedural effect of the prediction-motion task. In conclusion, task-irrelevant local motion and global motion are neither averaged in a simple manner nor are they processed independently.     

Racial-Ethnic Differences in Genetic Amniocentesis Uptake

The objective of this study was to determine the role of health beliefs in genetic amniocentesis acceptance in a diverse racial-ethnic population. Participants completed a previously-validated questionnaire consisting of three sections: (1) demographics, (2) amniocentesis knowledge, and (3) health beliefs, which assessed perceived susceptibility, seriousness of potential impact, benefits of testing, and barriers to testing. The results showed that Hispanic women were less likely to accept amniocentesis (51.5% vs. Caucasian 82.8%, African American 82.9%, Asian 82.8%). Education level was the only demographic factor higher among acceptors. Women who accepted amniocentesis had higher perceived seriousness, susceptibility, and benefits HBM scores and higher knowledge scores than women who declined. HBM scores and knowledge predicted the amniocentesis decision correctly 91.5% of the time. Individual health beliefs and knowledge play a greater role in genetic amniocentesis acceptance than do demographic factors such as race-ethnicity.     

The contingent smile: a meta-analysis of sex differences in smiling

The authors present a meta-analysis of sex differences in smiling based on 448 effect sizes derivedfrom 162 research reports. There was a statistically significant tendency for women and adolescent girls to smile more than men and adolescent boys (d = 0.41). The authors hypothesized that sex differences in smiling would be larger when concerns about gender-appropriate behavior were made more conspicuous, situational constraints were absent or ambiguous, or emotion (especially negative) was salient. It was also predicted that the size of the sex difference in smiling would vary by culture and age. Moderator analysis supported these predictions. Although men tend to smile less than women, the degree to which this is so is contingent on rules and roles.     

Sources of individual differences in fraction skills

The purpose of this investigation was to evaluate a conceptual model of relations between two kinds of mathematical knowledge (simple arithmetic and conceptual knowledge), two kinds of child characteristics (working memory and on-task related classroom behavior), and individual differences in three kinds of fraction outcomes (fraction computation, estimation, and word problems) in 105 fifth grade students. Structural equation modeling provided consistent evidence that conceptual knowledge independently contributes to individual differences in the three fraction outcomes. Simple arithmetic knowledge was uniquely related only to variability in fraction computation skills. Mathematical knowledge was found to mediate some of the contributions of both working memory and classroom behavior on variability in fraction outcomes. These supported mediating processes extend the current literature by explication of the pathways via which characteristics of children may affect individual differences in fraction outcomes.     

Time and resource limits on working memory: cross-age consistency in counting span performance

This longitudinal study separated resource demand effects from those of retention interval in a counting span task among 100 children tested in grade 2 and again in grades 3 and 4. A last card large counting span condition had an equivalent memory load to a last card small, but the last card large required holding the count over a longer retention interval. In all three waves of assessment, the last card large condition was found to be less accurate than the last card small. A model predicting reading comprehension showed that age was a significant predictor when entered first accounting for 26% of the variance, but counting span accounted for a further 22% of the variance. Span at Wave 1 accounted for significant unique variance at Wave 2 and at Wave 3. Results were similar for math calculation with age accounting for 31% of the variance and counting span accounting for a further 34% of the variance. Span at Wave 1 explained unique variance in math at Wave 2 and at Wave 3.