Genetic and Environmental Influences on the Development and Stability of Executive Functions in Children of Preschool Age: A Longitudinal Study of Japanese Twins

Executive functions (EF) are an important predictor of later adaptive development. A number of environmental influences, such as parenting, have been suggested as important promoters of EF development. However, behavioural genetic research has demonstrated that many environmental influences could be affected by genetic influences. Therefore, it is important to consider genetic variations when investigating environmental influences on EF development in children. To date, few studies have used genetically informative designs to assess the etiology of EF development during the preschool years, a period of rapid development. As a result, it remains unclear how and to what extent the environmental influences that are not confounded by genetic influences affect EF development during this developmental period. The present study explored EF development during the preschool years using a longitudinal and genetically informative design and a non‐Western population. Japanese twins were visited at their homes and individually tested on EF measures at 24, 36, and 48 months of age. Phenotypic correlations and confirmatory factor analyses suggested that EF are less cohesive at 24 months of age and emerge as a common single factor at 36 and 48 months. Additionally, longitudinal and multivariate behavioural genetic analyses indicated that the EF developmental change during this period is promoted by both shared and nonshared environmental influences as well as genetic influences, while EF stability is brought about by shared environments. The present findings elucidated the etiology of EF development during the preschool years and confirmed that this period is an important transitional stage for EF development. Copyright © 2016 John Wiley & Sons, Ltd.     

Mind perception of God in Japanese children

There is a theoretical debate regarding whether children represent God with reference to a human. Most previous studies have assessed this issue focusing on knowledge/omniscience in western children. This study used a theoretical framework characterising mental capacities in terms of motivational/emotional (experience) and cognitive (agency) mental capacities and tested whether Japanese children discriminated between God, a human, a baby and an invisible agent according to these capacities. Three‐ to 6‐year‐old children were asked about the experience and agency of the agents. The results revealed that children discriminated God from a human in terms of mental capacities including experience and agency in 3‐year‐old children. On the other hand, 4‐ to 6‐year‐old children, but not 3‐year‐old children, discriminated a human from a baby and an invisible person. The results suggest that the Japanese children's representations of God differed from their representation of a human during preschool years.     

Nothingness,Meinongianism and inconsistent mereology

Synthese - Within the framework of Meinongianism, nothingness turns out to have contradictory features—it seems to be an object and not. In this paper, we explore two different kinds of...     

A biomechanical analysis of the 'high guard' position of arms during walking in toddlers

In this study, we investigated biomechanical contributions of the high guard position of the arms observed only in a subgroup of toddlers at very early stages of gait development. Six healthy toddlers who showed this peculiar arm posture were involved in this study. They participated in two data collection sessions (1 month apart). We used three-dimensional analysis of arm posture during gait to estimate the changes in forces and torques generated by the arms and acting on the upper trunk segment. Across visits, toddlers’ increase in walking speeds coincided with lowering arm postures. Despite the apparent trend of changes in arm posture in this group of toddlers, the interaction between arm posture and upper trunk position created a variety of changes in forces and torques among individuals. Findings of this study exhibited an example of the exploration of dynamics by toddlers in the early stage of gait development.     

Prevalence of imaginary companions in Japanese children

Having an imaginary companion (IC) is an example of children's pretend play. However, most research regarding children's ICs is from Western cultures. In this study, the prevalence of ICs was assessed among Japanese children (2‐ to 9‐year‐old children, N = 800). The developmental (age), biological (sex), and environmental (birth order) effects on Japanese children's ICs were also assessed. Moreover, whether IC status can be an indicator of fantasy orientation in Japanese children was examined. The results revealed that the prevalence of the invisible friend was relatively rare, but the personified object was prevalent in Japanese children. Age and sex, but not birth order, significantly affected the prevalence of ICs in Japan. Moreover, IC status significantly indicated children's fantasy orientation. The results suggest that the characteristics of Japanese children's ICs are partly different from those in Western children. Social‐cultural contexts can affect this difference.     

The effects of warned loss magnitude and timeout duration on human avoidance behavior

This study experimentally investigated the determinants of avoidance behavior when participants are forewarned of aversive outcomes. The effects of 3 variables on avoidance behavior were examined: point-loss amount (5 levels, from 20 to 100 points), duration of timeout from positive reinforcement (5 levels, 20 to 100 s), and 3 predictive accuracy levels (100%, 50%, and 0%) of warning stimuli. Twelve participants completed 3 sessions, each comprising 25 discrete trials, that differed in predictive accuracy level. Throughout a session, a participant engaged in button press responses that were reinforced by points under a conjunctive fixed-ratio fixed-interval schedule. During each trial, a warning stimulus that indicated a loss amount and a timeout duration was presented. If the participant pressed the avoidance button, then the timeout started, otherwise the loss occurred. The trial ended with termination of timeout or an occurrence of the loss. Results showed that avoidance responses increased when the loss amount increased and decreased when the timeout duration increased. The frequency of avoidance responses was lowest when the predictive accuracy of warning stimuli was 0%. These findings demonstrated that this experimental procedure could be useful for investigating human avoidance behavior outside the laboratory.     

Conserved evolutionary history for quick detection of threatening faces

Humans quickly recognize threats such as snakes and threatening faces, suggesting that human ancestors evolved specialized visual systems to detect biologically relevant threat stimuli. Although non-human primates also detect snakes quickly, it is unclear whether primates share the efficient visual systems to process the threatening faces of their conspecifics. Primates may not necessarily process conspecific threats by facial expressions, because threats from conspecifics in natural situations are often accompanied by other cues such as threatening actions (or attacks) and vocal calls. Here, we show a similar threat superiority effect in both humans and macaque Japanese monkeys. In visual search tasks, monkeys and humans both responded to pictures of a threatening face of an unfamiliar adult male monkey among neutral faces faster than to pictures of a neutral face among threatening faces. However, the monkeys’ response times to detect deviant pictures of a non-face stimulus were not slower when it was shown among threat faces than when it was shown among neutral faces. These results provide the first evidence that monkeys have an attentional bias toward the threatening faces of conspecifics and suggest that threatening faces are evolutionarily relevant fear stimuli. The subcortical visual systems in primates likely process not only snakes, but also more general biological threat-relevant stimuli, including threatening conspecific faces.     

“Granny dumping”: Acceptability of sacrificing the elderly in a simulated moral dilemma

In a simulated moral dilemma, most people would be willing to endorse killing a single individual to save five others, but do people show the same degree of resistance to sacrificing people of different ages? In the present study, participants were asked to choose how acceptable it was to sacrifice one individual from a number of different age groups in order to save five others in a trolley problem. The sacrificial targets were a 70‐year‐old male stranger, a 20‐year‐old male stranger, a 5‐year‐old male stranger, or a 20‐year‐old male disabled stranger. Our results indicated that more participants accepted sacrificing the elderly stranger than the other three targets; sacrificing the child was the least accepted option. These results indicate that the decision‐making process in a moral dilemma involves weighing others' lives according to their age and implicitly predicting their life span.     

Changes in Pigeons’ Responses to Numerical Stimuli Depending on Total Element Area Differences between Stimuli

The Psychological Record - This experiment investigated whether pigeons’ response to numerical stimuli in a numerosity discrimination task differed by degree of difference in total element...     

Atomic structure and solute segregation of a Σ = 3, [110]/{111} grain boundary in an yttria-stabilized cubic zirconia bicrystal

The atomic structure and chemical composition of a =3, [110]/{111} symmetric tilt grain boundary in an yttria-stabilized cubic zirconia bicrystal has been investigated by high-resolution transmission electron microscopy (HRTEM) and nanoprobe energy-dispersive X-ray spectroscopy. The experimental HRTEM images are compared with simulated images for a model obtained by lattice statics calculations. It is found that the grain boundary has two individual mirror symmetrical planes in cation and anion sublattices. In this case, the cations are forced to form sevenfold coordination in the vicinity of the boundary owing to the restraint of the boundary structure, while the cations in the cubic fluorite structure have eightfold coordination. The segregation of yttrium ions was experimentally detected at the = 3 boundary, a finding that is considered to be closely related to the change in the local coordination at the boundary.