The adrenergic receptor α-2A gene (ADRA2A) and neuropsychological executive functions as putative endophenotypes for childhood ADHD

There is resurgent interest in the psychiatric literature in endophenotypes, variables thought to more strongly reflect the effects of candidate genes than do manifest disorders. In a sample of 176 children with attention deficit hyperactivity disorder (ADHD) and 52 of their siblings, we examined the validity of several putative endophenotypes for ADHD that represent commonly used clinical measures of multiple cognitive/neuropsychological domains of executive functions (EFs). We review their distributional normality, their relations to ADHD symptoms in probands and unaffected siblings relative to nonADHD controls, and their correlation in siblings. We also tested the EF measures’ associations with the ADRA2A gene and whether they mediated or moderated the associations between ADHD and ADRA2A. Several EF measures showed association with ADRA2A, as well as moderation, but not mediation, of its association with ADHD. Implications of the results for evaluating the validity and utility of putative endophenotype measures and for finding candidate gene effects on ADHD are discussed.     

Cultural differences in neural function associated with object processing

Behavioral research suggests that Westerners focus more on objects, whereas East Asians attend more to relationships and contexts. We evaluated the neural basis for these cultural differences in an event-related fMRI study. East Asian and American participants incidentally encoded pictures of (1) a target object alone, (2) a background scene with no discernable target object, and (3) a distinct target object against a meaningful background. Americans, relative to East Asians, activated more regions implicated in object processing, including bilateral middle temporal gyrus, left superior parietal/angular gyrus, and right superior temporal/supramarginal gyrus. In contrast to the cultural differences in object-processing areas, few differences emerged in background-processing regions. These results suggest that cultural experiences subtly direct neural activity, particularly for focal objects, at an early stage of scene encoding.     

DSM-defined anxiety disorders symptoms in South African youths: Their assessment and relationship with perceived parental rearing behaviors

This study investigated DSM-defined anxiety symptoms in South African youths. Children and adolescents (N = 701) from various cultural groups completed the SCARED and a questionnaire measuring perceived parental rearing behaviors. Results indicated that the psychometric properties of the SCARED were satisfactory in the total sample of South African youths, and acceptable in colored and black children and adolescents. Further, colored and black youths displayed higher SCARED scores than white youths, and there were also differences in the perceived parental rearing behaviors of the cultural groups. White youths generally rated their parents' rearing behaviors as less anxious, overprotective, and rejective, but more emotionally warm than colored and black youths. Finally, positive correlations were found between anxious rearing, overprotection, and rejection and anxiety symptoms. The clinical and research implications of these findings are briefly discussed.     

Boys withdraw more in one-on-one interactions, whereas girls withdraw more in groups

Past research predicts that males will be more likely to withdraw in one-on-one interactions versus groups, whereas females will be more likely to withdraw in groups than in one-on-one interactions. Ninety-eight 10-year-old children engaged in a word generation task either in same-sex dyads or in groups. Boys completed significantly more words in groups than in dyads, whereas girls' performance was similar in the 2 social structures. Confirming the hypothesis, analyses of the dynamics of dyads and groups using time spent writing as a measure of effort demonstrated that boys withdrew more than girls in dyads, whereas girls withdrew more than boys in groups. Furthermore, in groups, girls were more likely than boys to focus on one individual. Causal explanations for sex differences in preferences for differing social structures are proposed.     

The impact of secondary tasks on multi-tasking in a virtual environment

One experiment is described that examined the possible involvement of working memory in the Virtual Errands Test (McGeorge et al. (2001). Using virtual environments in the assessment of executive dysfunction. Presence, 10, 375-383), which requires participants to complete errands within a virtual environment, presented on a computer screen. Time was limited, therefore participants had to swap between tasks (multi-task) efficiently to complete the errands. Forty-two undergraduates participated, all attempting the test twice. On one of these occasions they were asked to perform a concurrent task throughout (order of single and dual-task conditions was counterbalanced). The type of secondary task was manipulated between groups. Twenty-one participants were asked to randomly generate months of the year aloud in the dual-task condition, while another 21 were asked to suppress articulation by repeating the word "December". An overall dual-task effect on the Virtual Errands Test was observed, although this was qualified by an interaction with the order of single and dual-task conditions. Analysis of the secondary task data showed a drop in performance (relative to baseline) under dual-task conditions, and that drop was greater for the random generation group than the articulatory suppression group. These data are interpreted as suggesting that the central executive and phonological loop components of working memory are implicated in this test of multi-tasking.     

How do we decide whom our friends are? Defining levels of friendship in Poland and the United States

Participants were 57 U.S. college students and 56 Polish university students and copper mine workers who judged the intimacy of 9 hypothetical relationships and also rated the intensity of their relationships with a best friend, a friend, and an acquaintance on the Friendship Intensity Measurement Scale (FIMS; T. S. Arunkumar & B. Dharmangadan, 2001). The present results confirmed that people perceive (a) relationships with best friends as more intense and intimate than other friendships and (b) other friendships as more intense and intimate than acquaintanceships. The results also indicated that Americans perceive all of their relationships, ranging from mere acquaintanceships to intimate friendships, as more intense and intimate than do Poles. It was somewhat surprising that there were no sex differences in either country in the perception of relationships. The authors discussed the research in the context of the difficulty of defining what friendship is and how an individual's cultural background might interact with person variables such as age and sex.     

The historiography of Swedish sociology and the bounding of disciplinary identity

Bounding a scientific discipline is a way of regulating its cognitive direction as well as its relations to neighboring disciplines and extra-academic authorities. In this process of identity making, disciplinary history often is a crucial element. In this article, focusing on the historiography of Swedish sociology and the reception of Gustaf Steffen, Sweden's first professional sociologist, it is argued that Steffen's marginalized role in the traditional accounts should be understood not only with reference to his supposed theoretical shortcomings, but also in the historical context of the early postwar reestablishment of sociology as an academic discipline and its prevalent need for a new disciplinary identity, strategically adjusted to the contemporary institutional and political settings.     

Aging and the perception of 3-D shape from dynamic patterns of binocular disparity

In two experiments, we investigated the ability of younger and older observers to perceive and discriminate 3-D shape from static and dynamic patterns of binocular disparity. In both experiments, the younger observers' discrimination accuracies were 20% higher than those of the older observers. Despite this quantitative difference, in all other respects the older observers performed similarly to the younger observers. Both age groups were similarly affected by changes in the magnitude of binocular disparity, by reductions in binocular correspondence, and by increases in the speed of stereoscopic motion. In addition, observers in both age groups exhibited an advantage in performance for dynamic stereograms when the patterns of binocular disparity contained significant amounts of correspondence "noise." The process of aging does affect stereopsis, but the effects are quantitative rather than qualitative.     

Environmental coupling modulates the attractors of rhythmic coordination

A simple instance of coupling behavior to the environment is oscillating the hands in pace with metronome beats. This environmental coupling can be weaker (1 beat per cycle) or stronger (2 beats per cycle). The authors examined whether strength of environmental coupling enhanced the stability of in-phase bimanual coordination. Detuning by manipulanda that produced different left and right eigenfrequencies shifted the relative phase angle from 0 degrees, with the size of the shift larger for higher movement frequencies. Stronger environmental coupling was found to decrease this relative-phase shift, with accompanying increase and reduction, respectively, in recurrence quantification measures related to coordination stability and coordination noise. Stronger environmental coupling also increased oscillation amplitude. Results are considered from the perspective of parametric stabilization.     

A contextual interference account of distinctiveness effects in recognition

In this article, we report on two experiments that aimed to shed light on the memorability effect that derives from varying the uniqueness of contextual cues presented at encoding and retrieval. We sought to understand the locus of the recognition advantage for studying and testing words with nominally irrelevant features that are rarely shared with other words ("low-fan" features) as compared with features that are studied with more words ("high-fan" features). Each word was studied with one high-fan feature and one low-fan feature, but only one of the two features was reinstated at test. Recognition judgments were more accurate when the low-fan feature was reinstated than when the high-fan feature was reinstated. The data suggest that encoding cues that suffer from contextual interference negatively affect retrieval and do so by hindering recollection-based processing.