Interactions between serotonin transporter gene haplotypes and quality of mothers' parenting predict the development of children's noncompliance

The LPR and STin2 polymorphisms of the serotonin transporter gene (SLC6A4) were combined into haplotypes that, together with quality of maternal parenting, were used to predict initial levels and linear change in children's (N = 138) noncompliance and aggression from age 18-54 months. Quality of mothers' parenting behavior was observed when children were 18 months old, and nonparental caregivers' reports of noncompliance and aggression were collected annually from 18 to 54 months of age. Quality of early parenting was negatively related to the slope of noncompliance only for children with the LPR-S/STin2-10 haplotype and to 18-month noncompliance only for children with haplotypes that did not include LPR-S. The findings support the notion that SLC6A4 haplotypes index differential susceptibility to variability in parenting quality, with certain haplotypes showing greater reactivity to both supportive and unsupportive environments. These different genetic backgrounds likely reflect an evolutionary response to variation in the parenting environment.     

Individual and social network predictors of the short‐term stability of bullying victimization in the United Kingdom and Germany

Background. There is still relatively little research on the social context within which bullying develops and remains stable. Aim. This study examined the short‐term stability of bullying victimization among primary school students in the United Kingdom and Germany (mean age, 8.9 years) and the individual and social network factors that contributed to remaining a victim of bullying. Sample. The sample consisted of 454 children (247 males and 207 females). Methods. Participants completed questionnaires on bullying victimization at three assessment points over a 9‐week period. Other measures consisted of self‐reported demographic, peer, and family relationship characteristics. Social network indices of density, reciprocity, and hierarchy were constructed using friendship and peer acceptance nominations. Results. Relative risk analyses indicated a six‐fold increased risk of remaining a victim at consequent follow‐ups, compared to a child not victimized at baseline becoming a victim over the follow‐up period. Individual characteristics explained substantially more variance in the stability of bullying victimization than class‐level factors. Hierarchical logistic regression analyses revealed that being victimized by siblings and being rejected by peers predicted remaining a victim over a 9‐week period. Conclusions. Bullying victimization among primary school students proved moderately stable over a 9‐week period. Individual characteristics were more influential in predicting the stable victim role than class‐level factors. Our findings have implications for the identification of stable victims in primary school and early preventative bullying programs.     

Long-term transfer of learning from books and video during toddlerhood

Television viewing and picture book reading are prevalent activities during toddlerhood, and research has shown that toddlers can imitate from both books and videos after short delays. This is the first study to directly compare toddlers' long-term retention rates for target actions learned from a video or book. Toddlers (N=158) at 18- and 24-months of age saw an experimenter demonstrating how to make a novel three-step toy rattle via a prerecorded video or a picture book. The toddlers' imitation of the target actions was tested after a specific delay (e.g., 2, 4 weeks), and their performance was compared with that of age-matched controls who did not see a demonstration. The 18-month-olds retained the target actions for 2 weeks, exhibiting forgetting at 4 weeks, whereas the 24-month-olds retained the information for up to 4 weeks, exhibiting forgetting at 8 weeks. Retention rates for books and videos did not differ at either age. These findings demonstrate very impressive retention from a brief two-dimensional media demonstration, and they contribute to our overall understanding of long-term memory processes during infancy.     

You deplete me: The cognitive costs of colorblindness on ethnic minorities

This study examined how priming Whites with colorblind or multicultural approaches to diversity prior to an interracial interaction affects ethnic minorities' cognitive functioning. Although ethnic minorities did not explicitly know which prime their White partner received, ethnic minorities paired with Whites primed with colorblindness (vs. multiculturalism) showed poorer cognitive performance on the Stroop (1935) color-naming task following the interaction. Furthermore, Whites in interracial interactions primed with colorblindness exhibited more behavioral prejudice, which mediated ethnic minorities' decreased cognitive performance. These findings suggest that Whites' exposure to certain ideologies may affect the cognitive performance of the ethnic minorities they encounter.     

Using a modified lag task to measure adult age differences in working memory

Four groups of adults, ages 40 to 70+ years, took the Modified Lag Task which requires that participants remember lists of words and subsequently recall the first, second, or third word from the end of the list. Previously, the task showed convergent validity with the operation span (a complex span measure) and a divergent validity with the digit span (a simple span measure). To establish predictive validity, the present study was designed to assess if this task could separate four age groups in working memory performance. The present study found support for the validity of the Modified Lag Task; however, additional research is warranted to further develop the construct validity of this task.     

Statistical judgments are influenced by the implied likelihood that samples represent the same population

When sample information is combined, it is generally considered normative to weight information based on larger samples more heavily than information based on smaller samples. However, if samples appear likely to have been drawn from different subpopulations, it is reasonable to combine estimates of these subpopulation means (typically, the sample means) without weighting these estimates by sample size. This study investigated whether laypeople are influenced by the likelihood of samples coming from the same population when determining how to combine information. In two experiments we show that (1) implied binomial variability affected participants’ judgments of the likelihood that a sample was drawn from a given population, (2) participants' judgments were more affected by sample size when samples were implied to be drawn randomly from a general population, compared to when they were implied to be drawn from different subpopulations, and (3) people higher in numeracy gave more normative responses. We conclude that when determining how to weight and combine samples, laypeople use not only the provided data, but also information about likelihood and sampling processes that these data imply.     

Influence of bilingualism on memory generalization during infancy

Very few studies have examined the cognitive advantages of bilingualism during the first two years of development, and a majority of the studies examining bilingualism throughout the lifespan have focused on the relationship between multiple languages and cognitive control. Early experience with multiple language systems may influence domain‐general processes, such as memory, that may increase a bilingual child’s capacity for learning. In the current study, we found that bilingual, but not monolingual, infants were able to generalize across cues at 18 months. This is the first study to show a clear bilingual advantage in memory generalization, with more equal or balanced exposure to each language significantly predicting ability to generalize. A video abstract of this article can be viewed at http://www.youtube.com/watch?v=31QsMqYtGGo&feature=plcp