Emergence of a Gene x socioeconomic status interaction on infant mental ability between 10 months and 2 years

Recent research in behavioral genetics has found evidence for a Gene × Environment interaction on cognitive ability: Individual differences in cognitive ability among children raised in socioeconomically advantaged homes are primarily due to genes, whereas environmental factors are more influential for children from disadvantaged homes. We investigated the developmental origins of this interaction in a sample of 750 pairs of twins measured on the Bayley Short Form test of infant mental ability, once at age 10 months and again at age 2 years. A Gene × Environment interaction was evident on the longitudinal change in mental ability over the study period. At age 10 months, genes accounted for negligible variation in mental ability across all levels of socioeconomic status (SES). However, genetic influences emerged over the course of development, with larger genetic influences emerging for infants raised in higher-SES homes. At age 2 years, genes accounted for nearly 50% of the variation in mental ability of children raised in high-SES homes, but genes continued to account for negligible variation in mental ability of children raised in low-SES homes.     

On the Links Between Attachment Style, Parental Rearing Behaviors, and Internalizing and Externalizing Problems in Non-Clinical Children

  We sought to investigate the relationships between negative family factors such as insecure attachment and adverse parental rearing, and internalizing and externalizing symptoms in a large sample of non-clinical children (N = 237) aged 9 to 12 years. All children completed a set of self-report questionnaires including a single-item measure of attachment style towards the mother and the father as well as an index of perceived parental rearing behaviors. Further, measures of internalizing symptoms (e.g., anxiety and depression) and externalizing symptoms (e.g., aggression) were completed. Results showed that perceived rearing behaviors of both mother and father (in particular rejection and anxious rearing) consistently accounted for a significant proportion of the variance in internalizing and externalizing symptoms. Attachment style was found to play a less prominent role. Some support for gender-specific relationships was found, indicating that the presence of negative family factors in fathers had more impact on symptoms in boys, whereas the presence of such factors in the mothers had more influence on symptoms in girls. Altogether, these results suggest that in addition to common pathways by which both parents promote psychopathological symptoms in children, there may also be separate pathways by which the father or the mother may have a unique impact on the development of such symptoms in boys or girls respectively.     

Postscript: sortal concepts are fundamental for tracing identity

Our discussion with Rips, Blok, and Newman (2006; Blok, Newman, & Rips, in press; Rhemtulla & Xu, in press) has brought together theory and evidence from researchers in adult cognition and those in infant development. By this point, researchers all recognize that any theory of concepts of individuals must consider the evidence from infants' first concepts as well as explicit adult reasoning tasks. Despite this agreement, we continue to disagree on several fundamental issues.     

Monkey business: Children’s use of character identity to infer shared properties

Children’s toys provide a rich arena for investigating conceptual flexibility, because they often can be understood as possessing an individual identity at multiple levels of abstraction. For example, many dolls (e.g., Winnie-the-Pooh) and action figures (e.g., Batman) can be construed either as characters from a fictional world or as physical objects in the real world. In two experiments, 72 4- and 5-year-olds took part in a property extension task, the results of which provide evidence of an understanding that (1) two representations of a character share certain properties in virtue of their shared character identity, and this sharing does not stem simply from having the same name, and (2) one representation of a character is more likely to share properties with another representation of the character if the properties were acquired by the character than if they were acquired by the representation. Children’s understanding of a representational object’s abstract character identity thus enabled them to transcend using its unique spatio-temporal history as a sole basis for inferring its idiosyncratic properties.     

When can categorical variables be treated as continuous? A comparison of robust continuous and categorical SEM estimation methods under suboptimal conditions

A simulation study compared the performance of robust normal theory maximum likelihood (ML) and robust categorical least squares (cat-LS) methodology for estimating confirmatory factor analysis models with ordinal variables. Data were generated from 2 models with 2-7 categories, 4 sample sizes, 2 latent distributions, and 5 patterns of category thresholds. Results revealed that factor loadings and robust standard errors were generally most accurately estimated using cat-LS, especially with fewer than 5 categories; however, factor correlations and model fit were assessed equally well with ML. Cat-LS was found to be more sensitive to sample size and to violations of the assumption of normality of the underlying continuous variables. Normal theory ML was found to be more sensitive to asymmetric category thresholds and was especially biased when estimating large factor loadings. Accordingly, we recommend cat-LS for data sets containing variables with fewer than 5 categories and ML when there are 5 or more categories, sample size is small, and category thresholds are approximately symmetric. With 6-7 categories, results were similar across methods for many conditions; in these cases, either method is acceptable. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Categorical perception of morphed objects using a free-naming experiment

Morphed figures entail a dominant and nondominant interpretation. Testing perception of morphed objects using forced-choice methods demonstrates that morphed figures are perceived as their dominant interpretation (“categorical perception”, or CP). Using a more natural free-naming response could reveal whether CP is an effect independent of method. In Experiment 1, therefore, series of morphed figures were tested for CP using free naming. Half of the morph series were identified as CP patterns. In Experiment 2, we used forced choice to investigate CP, resulting in an increase of number of CP series compared to free naming. The overlap between CP series of Experiments 1 and 2 was small, however. Experiment 3 revealed that higher perceptual similarity between the extremes of the series was strongly related to CP for the free-naming method, in contrast to the forced-choice method. We conclude that the observation of CP depends on the intactness of the intrinsic object structure caused by the morphing procedure.     

The performance of robust test statistics with categorical data

This paper reports on a simulation study that evaluated the performance of five structural equation model test statistics appropriate for categorical data. Both Type I error rate and power were investigated. Different model sizes, sample sizes, numbers of categories, and threshold distributions were considered. Statistics associated with both the diagonally weighted least squares (cat‐DWLS) estimator and with the unweighted least squares (cat‐ULS) estimator were studied. Recent research suggests that cat‐ULS parameter estimates and robust standard errors slightly outperform cat‐DWLS estimates and robust standard errors ( Forero, Maydeu‐Olivares, & Gallardo‐Pujol, 2009 ). The findings of the present research suggest that the mean‐ and variance‐adjusted test statistic associated with the cat‐ULS estimator performs best overall. A new version of this statistic now exists that does not require a degrees‐of‐freedom adjustment ( Asparouhov & Muthén, 2010 ), and this statistic is recommended. Overall, the cat‐ULS estimator is recommended over cat‐DWLS, particularly in small to medium sample sizes.     

the inventory of recent life experiences for cancer patients (IRLE-C): A decontaminated measure of cancer-based hassles

Abstract

Cancer is recognized to have multifaceted stressful impact on all areas of a patient's life. Researchers commonly use self-report questionnaires, intended to measure stressors objectively. However, the item-content and response-format of such scales often tap physical and mental responses to stress, thereby contaminating prediction of adverse impact. This article reports the development and validation of English and French versions of the Inventory of Recent Life Experiences for Cancer Patients (IRLE-C) which is designed to minimize such “criterion-contamination”. This entailed (1) avoiding items reflecting physical or subjective distress; (2) rating stressors for degree of exposure only; and (3) use of an innocuous scale title. The initial item pool was administered serially to a sample of 100 Francophone breast-cancer and prostate-cancer patients. To guard against inflating reliability and validity estimates through capitalizing on chance, we administered the 30-item final scale to an independent sample of 96 Francophone breast-cancer and prostate-cancer patients undergoing radiation treatment. Following the item-selection step, factorial structure and validity analyses were performed using the combined French-speaking sample (n= 196). Second, we administered the English version of the scale to an English-speaking sample of 127 cancer patients (various cancer sites and stages). The measure showed good internal consistency (.94 and .89 for the Francophone and Anglophone samples respectively) and met criteria for a 2-week test-retest reliability (r= .70 for the item-selection subsample and .80 for the cross-replication sub-sample). Correlations between the IRLE-C and the POMS Total Mood Disturbance were around .60 for both the Francophone and Anglophone samples. Avoiding contamination (through content and format) without losing its relationship to subjective distress, the IRLE-C appears a useful instrument for applying the stress-process model in oncology to establish clear distinctions among stressors, mediators, reactions, and consequences.     

Using genetic programming to discover nonlinear variable interactions

Psychology has to deal with many interacting variables. The analyses usually used to uncover such relationships have many constraints that limit their utility. We briefly discuss these and describe recent work that uses genetic programming to evolve equations to combine variables in nonlinear ways in a number of different domains. We focus on four studies of interactions from lexical access experiments and psychometric problems. In all cases, genetic programming described nonlinear combinations of items in a manner that was subsequently independently verified. We discuss the general implications of genetic programming and related computational methods for multivariate problems in psychology.