Are infants in the dark about hidden objects?

Infants appear to search for objects hidden by darkness earlier in development than they search for objects hidden by an occluder in the light. However, these two types of search tasks have differed in numerous ways that may have contributed to better performance in the dark (e.g. in whether the hidden objects made sound, in the number of familiarization trials with visible objects). The current studies controlled such incidental differences between search tasks, so that they could be directly compared. Six‐and‐a‐half‐month‐olds received four types of test events, in which either a toy or no toy was presented and then hidden in the dark or under a cloth in the light. Infants searched more often on toy than no‐toy trials in the dark than with a cloth. The advantage in searching for hidden objects in the dark thus appears to be genuine. Theoretical implications are discussed.     

Verbal ability and executive functioning development in preschoolers at head start

Research suggests that executive functioning skills may enhance the school readiness of children from disadvantaged homes. Questions remain, however, concerning both the structure and the stability of executive functioning among preschoolers. In addition, there is a lack of research addressing potential predictors of longitudinal change in executive functioning during early childhood. This study examined the structure of executive functioning from fall to spring of the preschool year using a multimethod battery of measures. Confirmatory factor analyses revealed a unidimensional model fit the data well at both time points, and tests of measurement invariance across time points indicated that children's mean latent executive functioning scores significantly improved over time. Verbal ability was a significant predictor of longitudinal change in executive functioning. Theoretical implications and directions for future research are discussed.     

Head Start and urban children's school readiness: a birth cohort study in 18 cities

We used longitudinal data from a birth cohort study, the Fragile Families and Child Wellbeing Study, to investigate the links between Head Start and school readiness in a large and diverse sample of urban children at age 5 (N = 2,803; 18 cities). We found that Head Start attendance was associated with enhanced cognitive ability and social competence and reduced attention problems but not reduced internalizing or externalizing behavior problems. These findings were robust to model specifications (including models with city-fixed effects and propensity-scoring matching). Furthermore, the effects of Head Start varied by the reference group. Head Start was associated with improved cognitive development when compared with parental care or other nonparental care, as well as improved social competence (compared with parental care) and reduced attention problems (compared with other nonparental care). In contrast, compared with attendance at pre-kindergarten or other center-based care, Head Start attendance was not associated with cognitive gains but with improved social competence and reduced attention and externalizing behavior problems (compared with attendance at other center-based care). These associations were not moderated by child gender or race/ethnicity.     

Sex differences in expressive drawing

We examined sex differences in expressive drawings produced by 105 boys and 105 girls aged 9-15 years. The drawings were classified according to the type of expressive strategy used to depict emotion (literal, content, abstract, or any combination of these), and rated according to the complexity of that strategy. A creative/divergent thinking task (figural form) was used to assess the relationship between expressive drawing and figural creativity. As predicted, girls scored higher than boys on the expressive drawing task. Specifically, girls relied less often on literal strategies alone and were more likely to combine literal expression with metaphorical (content and abstract) expression than boys. There was a linear relationship between expressive drawing and divergent thinking scores. These results are consistent with the idea that boys and girls differ in the expressive component of emotion, and suggest that these sex differences extend to the expressive drawing domain. They also suggest that divergent thinking may be involved in the ability to draw expressively.     

Probability all the Way Up

Richard Jeffrey’s radical probabilism (‘probability all the way down’) is augmented by the claim that probability cannot be turned into certainty, except by data that logically exclude all alternatives. Once we start being uncertain, no amount of updating will free us from the treadmill of uncertainty. This claim is cast first in objectivist and then in subjectivist terms.     

Self-reported changes in subjective health and anthrax vaccination as reported by over 900 Persian Gulf War era veterans

A 1999 study of United Kingdom servicemembers by Unwin, et al. recently found significant relationships between anthrax and other vaccinations, reactions to those vaccines, and later health problems for male current or former active military Gulf War veterans. Likewise, in 2000 Steele and in 1998 Gilroy found possible adverse effects of vaccinations on Gulf War veterans. However, the role of such vaccinations remains controversial; more recent government reports continue to dispute the existence of any data that might reflect adversely on the role of vaccinations on the health of Gulf War veterans. To address this controversy, the current study assessed similar relationships for over 900 Reserve Component Gulf War Era veterans from Ohio and nearby states. Gulf War veterans were more likely to report poorer health than non-Gulf veterans. Female veterans were more likely to report mild or severe reactions to vaccines than male veterans. Those veterans who received anthrax vaccine reported more reactions to vaccines than those who did not receive anthrax vaccine. Declines in long-term subjective health were associated with receipt of anthrax vaccine by Gulf War veterans but not for those who did not deploy to the Gulf, although few of the latter received anthrax vaccine. Regardless of deployment status, veterans who reported more severe reactions to vaccines were more likely to report declines in subjective health. Female veterans reported poorer health during the Gulf War than did male veterans, but sex was not related to veterans' reports of subjective health at subsequent times. It is recommended that servicemembers who experience severe reactions to anthrax vaccine be medically reevaluated before receiving further anthrax vaccine and that careful follow-ups be conducted of those receiving the vaccine currently, in accordance with Nass's 1999 recommendations. We also recommend that safer alternatives to thimerosal (a mercury sodium salt, 50% mercury) be used to preserve all vaccines.     

The acquisition of vector knowledge and its relation to self-rated direction sense

Self-rated sense of direction is reliably related to people's accuracy when pointing in the direction of unseen landmarks from imagined or actual perspectives. It is proposed that the cognitive substrate of accurate pointing responses is a vector representation, which is defined as an integrated network of displacement vectors. Experiment 1 isolated the body senses and tested displacement vector formation in a path-integration task. Experiment 2 isolated the visual modality and tested displacement vector formation in a virtual-learning task. Both experiments tested whether people reporting a good sense of direction (GSOD) were more likely to compute displacement vectors than people reporting a poor sense of direction (PSOD). The results showed that both GSOD and PSOD people computed displacement vectors in the path-integration task, but not in the virtual-learning task. When interlandmark relations were visually specified, GSOD people made more accurate pointing responses than PSOD people, adding to a growing body of cognitive correlates of self-rated direction sense.     

Family processes as pathways from income to young children's development

A variety of family processes have been hypothesized to mediate associations between income and young children's development. Maternal emotional distress, parental authoritative and authoritarian behavior (videotaped mother-child interactions), and provision of cognitively stimulating activities (Home Observation for Measurement of the Environment [HOME] scales) were examined as possible mediators in a sample of 493 White and African American low-birth-weight premature infants who were followed from birth through age 5. Cognitive ability was assessed by standardized test, and child behavior problems by maternal report, when the children were 3 and 5 years of age. As expected, family income was associated with child outcomes. The provision of stimulating experiences in the home mediated the relation between family income and both children's outcomes; maternal emotional distress and parenting practices mediated the relation between income and children's behavior problems.