Is the genetic structure of human personality universal? A cross-cultural twin study from North America, Europe, and Asia

This study examined whether universality of the 5-factor model (FFM) of personality operationalized by the Revised NEO Personality Inventory is due to genetic influences that are invariant across diverse nations. Factor analyses were conducted on matrices of phenotypic, genetic, and environmental correlations estimated in a sample of 1,209 monozygotic and 701 dizygotic twin pairs from Canada, Germany, and Japan. Five genetic and environmental factors were extracted for each sample. High congruence coefficients were observed when phenotypic, genetic, and environmental factors were compared in each sample as well as when each factor was compared across samples. These results suggest that the FFM has a solid biological basis and may represent a common heritage of the human species.     

The Relationship Between Academic Oral Proficiency and Reading Performance: A Comparative Study Between English Learners and English-Only Students

This study investigates the relationship between oral proficiency and reading proficiency in English-learning children (L2 students) and native English-speaking children (NE students). A set of oral activities measuring students’ academic oral skills in science classes was developed and administered to 61 fourth graders. Both the meaning-related aspects and the formal aspects of the students’ academic oral proficiency were compared between strong and struggling readers and between NE and L2 students. The study thus used a 2 × 2 factorial design (Strong/Struggling Readers × NE/L2 Students). After controlling for the students’ nonverbal analytic and reasoning skills, this study found that strong and struggling readers showed different levels of performance with respect to the meaning-related aspects of oral academic language but not with respect to the formal aspects of language. Conversely, differences between NE and L2 students were found in components related to the formal aspects but not in those related to the meaning aspects of oral language.     

Correlation between gray/white matter volume and cognition in healthy elderly people

This study applied volumetric analysis and voxel-based morphometry (VBM) of brain magnetic resonance (MR) images to assess whether correlations exist between global and regional gray/white matter volume and the cognitive functions of semantic memory and short-term memory, which are relatively well preserved with aging, using MR image data from 109 community-dwelling healthy elderly individuals. We used the Information and Digit Span subtests of the Wechsler Adult Intelligent Scale-Revised as measures of semantic memory and short-term memory, respectively. We found significant positive correlations between the gray matter ratio, the percentage of gray matter volume in the intracranial volume, and performance on the Digit Span subtest, and between the regional gray matter volumes of the bilateral anterior temporal lobes and performance on the Information subtest. No significant correlations between performance on the cognitive tests and white matter volume were found. Our results suggest that individual variability in specific cognitive functions that are relatively well preserved with aging is accounted for by the variability of gray matter volume in healthy elderly subjects.     

Interpreting the effects of image manipulation on picture perception in pigeons (Columba livia) and humans (Homo sapiens)

The effects of picture manipulations on humans' and pigeons' performance were examined in a go/no-go discrimination of two perceptually similar categories, cat and dog faces. Four types of manipulation were used to modify the images. Mosaicization and scrambling were used to produce degraded versions of the training stimuli, while morphing and cell exchange were used to manipulate the relative contribution of positive and negative training stimuli to test stimuli. Mosaicization mainly removes information at high spatial frequencies, whereas scrambling removes information at low spatial frequencies to a greater degree. Morphing leads to complex transformations of the stimuli that are not concentrated at any particular spatial frequency band. Cell exchange preserves high spatial frequency details, but sometimes moves them into the "wrong" stimulus. The four manipulations also introduce high-frequency noise to differing degrees. Responses to test stimuli indicated that high and low spatial frequency information were both sufficient but not necessary to maintain discrimination performance in both species, but there were also species differences in relative sensitivity to higher and lower spatial frequency information.     

Associations of Psychosocial Factors with Maternal Confidence Among Japanese and Vietnamese Mothers

We conducted this cross-sectional study among 392 Japanese and 294 Vietnamese mothers who attended routine child health visits in a Japanese city and at a tertiary hospital in Vietnam, in order to investigate the prevalence and associated sociodemographic, parenting, and psychological characteristics of low maternal confidence in child rearing among them. All data were collected from medical files in Japan, and from medical files and self-administered questionnaires in Vietnam. The proportion of mothers without secure feeling of confidence in the present study was 22% in Japan and 66% in Vietnam. Significant factors associated with a lack of confidence were first-time motherhood and unintended pregnancy in the Japanese dataset and younger age in the Vietnamese dataset. In both groups, a higher proportion of mothers who lacked confidence reported negative parenting outcomes than did confident mothers. Among the three psychological measurements (mood, self-efficacy and depression), higher self-efficacy was associated independently with a significantly reduced risk of not having confidence in child rearing. These results suggest the importance of developing parenting support programs to help Japanese and Vietnamese mothers, particularly those who are young, first-time mothers or who became pregnant unexpectedly, improve their self-efficacy.     

Discrimination of direction of movements in pigeons following previous experience of motion/static discrimination

Two experiments examined pigeons' discrimination of directional movement using pictorial images shown on computer monitors. Stimuli consisted of the movement of a bird against a stationary background or the movement of the background behind a stationary bird. In Experiment 1, pigeons were trained to discriminate either leftward or rightward motion of either the bird or the background from stationary frames drawn from the same movies. The background-discrimination group acquired the discrimination faster than the bird-discrimination group. In Experiment 2, transfer of the discrimination from the task of Experiment 1 to a discrimination between motion directions was examined. Most of the pigeons learned this discrimination rapidly, whereas in a pilot study in which direction discrimination was trained without previous static/movement discrimination, learning was poor. It appears that an experimental history of movement against stationary discrimination promoted the pigeons' learning of the directional motion discrimination.     

Unidimensional versus multidimensional approaches to the assessment of acculturation for Asian American populations

This study used generational status and the Suinn-Lew Asian Self-Identity Acculturation scale to examine unidimensional versus multidimensional approaches to the conceptualization and measurement of acculturation and their relationships to relevant cultural indicator variables, including measures of Individualism-Collectivism, Independent-Interdependent Self-Construal, Loss of Face, and Impression Management. Multivariate analyses of covariance and partial correlations were used to examine the relationship between the acculturation models and each set of cultural indicator variables while controlling for socioeconomic status. Given that acculturation differences are often cited as evidence for a culture effect between groups, the present findings of an uneven nature of these relationships as a function of the particular acculturation measurement strategy have important implications for research on Asian Americans.     

How can reward contribute to efficient self-control? Reinforcement of task-defined responses diminishes ego-depletion

We examined whether reinforcement learning of habitual actions diminishes ego depletion after a cognitive control task. Participants performed the Stroop task after a card selection task, in which one group was reinforced to respond to colors in the Stroop task (Stroop-color group) while another group was reinforced to respond to colors not in the Stroop task (non-Stroop-color group). We measured ego depletion in terms of decrement in endurance on an isometric handgrip task after the Stroop task. The Stroop-color group exhibited less decrease in their isometric handgrip endurance compared to the non-Stroop-color group. These results suggest that the former needed less effort for cognitive control during conflict processing, as reinforcement learning make task-defined response habitual. This finding provides a new perspective on the role of reward in cognitive control.