Methods for averaging alpha coefficients in reliability generalization studies

The reliability generalization (RG) approach is a kind of meta-analysis that aims to statistically integrate a set of independent reliability coefficients obtained in several applications of a test, with the purpose of characterizing the measurement error and determining which factors related to the studies and samples can explain its variability. Diverse procedures have been proposed in the literature for averaging a set of independent alpha coefficients, and there is no consensus about which methods are best. Here, we present the results of a Monte Carlo simulation study, comparing the performance of twelve procedures proposed in Feldt and Charter, in terms of bias and mean square error. These procedures differ from each other in the transformation (or not) of the coefficients, and in the application or not of a weighting scheme based on sample size. Our results recommend using weighted methods in contrast to unweighted ones, and transforming the coefficients by the Hakstian and Whalen's proposal or by the proposal based on the square root of the inverse alpha coefficient. Lastly, we discuss the relations between the diverse procedures for averaging alpha coefficients with fixed-effects, random-effects, and varying coefficients models.     

Developmental pattern of digit span in Spanish population

This study examined in a Spanish population the developmental pattern of digit span, as an index of one of the components of Baddeley's working memory--the phonological loop. A verbal digit span was administered to 570 participants ranging from 5 to 17 years old. The results indicated that the digit memory span increases until age 17 as opposed to Anglo-Saxon data--where it is established that this span reaches a peak by age 15. Additionally, these results were compared to the performance in the same task of healthy elderly, Alzheimer disease patients, and Frontotemporal dementia patients, examined in a previous study. The analysis shows that the phonological loop is affected by age and not so much by dementias.     

Low diversity and low frequency of participation in leisure activities compromise working memory efficiency in young adults

People perform leisure activities (LA) every day; pursuits that entail applying cognitive, physical and social abilities. As in old age, doing LA during early and middle adulthood is related to a reduced risk of dementias, probably by generating a cognitive reserve. As it is possible that a relation between doing LA and working memory (WM) efficiency exists in young adults, we assessed whether the diversity and frequency of LA are related to WM efficiency in this population. Ninety-three healthy young subjects solved the n-back task at two levels of difficulty (2, 3), and answered an LA questionnaire on the activities in which they had participated in the month prior to the experiment. Subjects were classified separately on their scores for (1) diversity (high/low) and (2) frequency (high/low) in order to test the relation between each variable and WM efficiency. Though no differences were found, a subsequent analysis of the average of diversity and frequency ratios of LA performance taken together-the diversity/frequency index-showed that low diversity plus low frequency was significantly associated with reduced WM efficiency at this age; results that suggest that frequent participation in diverse LA during youth is related to WM efficiency.     

The statistical signature of morphosyntax: A study of Hungarian and Italian infant-directed speech

Does statistical learning (Saffran, Aslin, &; Newport, 1996) offer a universal segmentation strategy for young language learners? Previous studies on large corpora of English and structurally similar languages have shown that statistical segmentation can be an effective strategy. However, many of the world’s languages have richer morphological systems, with sometimes several affixes attached to a stem (e.g. Hungarian: iskoláinkban: iskolá-i-nk-ban school.pl.poss1pl.inessive ‘in our schools’). In these languages, word boundaries and morpheme boundaries do not coincide. Does the internal structure of words affect segmentation? What word forms does segmentation yield in morphologically rich languages: complex word forms or separate stems and affixes? The present paper answers these questions by exploring different segmentation algorithms in infant-directed speech corpora from two typologically and structurally different languages, Hungarian and Italian. The results suggest that the morphological and syntactic type of a language has an impact on statistical segmentation, with different strategies working best in different languages. Specifically, the direction of segmentation seems to be sensitive to the affixation order of a language. Thus, backward probabilities are more effective in Hungarian, a heavily suffixing language, whereas forward probabilities are more informative in Italian, which has fewer suffixes and a large number of phrase-initial function words. The consequences of these findings for potential segmentation and word learning strategies are discussed.     

Cross cultural differences in unconscious knowledge

Previous studies have indicated cross cultural differences in conscious processes, such that Asians have a global preference and Westerners a more analytical one. We investigated whether these biases also apply to unconscious knowledge. In Experiment 1, Japanese and UK participants memorized strings of large (global) letters made out of small (local) letters. The strings constituted one sequence of letters at a global level and a different sequence at a local level. Implicit learning occurred at the global and not the local level for the Japanese but equally at both levels for the English. In Experiment 2, the Japanese preference for global over local processing persisted even when structure existed only at the local but not global level. In Experiment 3, Japanese and UK participants were asked to attend to just one of the levels, global or local. Now the cultural groups performed similarly, indicating that the bias largely reflects preference rather than ability (although the data left room for residual ability differences). In Experiment 4, the greater global advantage of Japanese rather English was confirmed for strings made of Japanese kana rather than Roman letters. That is, the cultural difference is not due to familiarity of the sequence elements. In sum, we show for the first time that cultural biases strongly affect the type of unconscious knowledge people acquire.     

The motor side of emotions: investigating the relationship between hemispheres, motor reactions and emotional stimuli

The aim of the present study was to analyze if the left hemisphere preferentially controls flexion responses toward positive stimuli, while the right hemisphere is specialized toward extensor responses to negative pictures. To this end, right-handed subjects had to pull or push a joystick subsequent to seeing a positive or a negative stimulus in their left or right hemifield. Flexion responses were faster for positive stimuli, while negative stimuli were associated with faster extensions responses. Overall, performance was fastest when emotional stimuli were presented to the left visual hemifield. This right hemisphere superiority was especially clear for negative stimuli, while reaction times toward positive pictures showed no hemispheric difference. We did not find any interaction between hemifield and response type. Neither was there a triple interaction between valence, hemifield and response type. We suppose that response dichotomies in humans are not as tightly linked to a hemisphere- and valence-bound reaction type as previously assumed.     

Agentic and Communal Personality Traits: Their Associations with Depression and Resilience among Transgender Women

Research reports the perpetuation of communal traits by transgender women, possibly to affirm their core gender identity. Transgender women in the United States are nearly 6 times more likely than the general population to experience significant depressive symptoms. Studies among non-transgender individuals in the United States demonstrate that agentic traits are associated with less depressive symptoms, while studies on communal traits are more inconsistent in their association with indicators of depression. Our study’s central objective was to examine the associations of agency and communion with depression and resilience (i.e., personal competence and acceptance of self and life) among transgender women living part-time and full-time in the female gender role. Participants in the United States were recruited through online and offline purposive sampling. One hundred and twenty-two transgender women (primarily Caucasian; ages ranging from 22 to 75) completed a web-based questionnaire. Results indicated that agentic and communal traits were significantly associated with decreased symptoms of depression and increased levels of resilience. One component of resilience – acceptance of self and life – mediated the relationship between agentic/communal traits and depression, however, for communal traits this pattern was only found for transgender women living in the female role full-time. There were no significant differences on depressive symptoms and one component of resilience - personal competence – among transgender women living full-time compared to transgender women living in the female role part-time. Transgender women living full-time in the female gender role reported higher levels of agentic/communal traits and acceptance of self and life compared to those living part-time in the female gender role. Our findings are discussed in the context of mental health among transgender women.     

Influence of background on precision of 3D depth judgment tasks in a real environment

Presently, little is known about the effect of curved backgrounds against which the target stimulus is presented on precision in stereoacuity. The experiment analyzed the influence of stimulus orientation and 3D background configuration on stereoscopic vision. Participants were instructed to perform 3D visual alignment tasks on a modified version of the Howard-Dolman apparatus, whereupon precision in depth perception for different curved backgrounds (flat, black, concave, and convex) was evaluated. In addition, the influence of stimulus orientation (0 degrees, 45 degrees, and 90 degrees) on precision was examined. The findings revealed an underestimation in the perceived depth in all background configurations, indicating highest and lowest precision outcomes for convex and concave backgrounds, respectively. In addition, a significant interaction of background and orientation was found. It was concluded that, in a real environment, background local depth cues are integrated with target stimuli to contribute to depth perception.