Shinji Yamagata

Nagoya University | Meidai · Department of Psychology and Human Developmental Sciences

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 monozygo...

J. M. Digman (1997) proposed that the Big Five personality traits showed a higher-order structure with 2 factors he labeled alpha and beta. These factors have been alternatively interpreted as heritable components of personality or as artifacts of evaluative bias. Using structural equation modeling, the authors reanalyzed data from a cross-national...

In the literature on achievement goals, performance-approach goals (striving to do better than others) and performance-avoidance goals (striving to avoid doing worse than others) tend to exhibit a moderate to high correlation, raising questions about whether the 2 goals represent distinct constructs. In the current article, we sought to examine the...

This twin study examined the bidirectional relationship between maternal parenting behaviors and children's peer problems that were not confounded by genetic and family environmental factors. Mothers of 259 monozygotic twin pairs reported parenting behaviors and peer problems when twins were 42 and 48 months. Path analyses on monozygotic twin diffe...

This study examined the extent to which the inequality of opportunity exists in Japan, using a classical twin design. Participants were 1,006 working, male twins (738 identical and 268 fraternal twins; age 20–60) recruited via a web-based survey. Participants responded to the questions of academic achievement at the ninth grade, years of educatio...

This study examined whether (1) self-presentation of extraversion/introversion changes the presenter’s explicit and implicit extraversion and (2) the presence of an audience informed of the presenter’s personal information moderates the effects. Sixty-two participants were randomly assigned to four conditions: 2 (trait presented: extraversion or in...

We examined whether people’s trait increases when asked to impress others with that trait. Participants (N=422) reported their extraversion/introversion and social desirability of extraversion and introversion. After 7 to 10 days, we asked them to write a self-introduction that gave either an extraverted or introverted impression, depending on thei...

This study examined whether high self-deceivers form their overly positive perception of their traits through overestimating their performance of self-presentation where they need to impress others as being extraverted/introverted, exhibiting more internalization of self-presentation (IOSP) of the trait. Participants were instructed to give either...

Differences in the frequency and differentiation of anger expression strategies, such as overt and constructive, and interpersonal contexts, such as parents and peers, were examined by sex and age in a community-based sample of 655 Japanese adolescents aged 9 to 16 years. The results revealed significant age-related differences in overt anger expre...

Background The comorbidity of depression and anxiety is associated with an increased risk of prolonged adverse mental health status. However, little is currently known about their genetic and environmental influences that help to explain both the comorbidity and distinctiveness. Using longitudinal twin data, the present study investigated both the...

Using a genetically informative design (about 2000 twin pairs), we investigated the phenotypic and genetic and environmental architecture of a broad construct of conscientiousness (including conscientiousness per se, effortful control, self-control, and grit). These four different measures were substantially correlated; the coefficients ranged from...

This study examined whether religiosity moderates the genetic and environmental etiology of the Big Five personality traits (Neuroticism, Extraversion, Openness to Experience, Agreeableness, and Conscientiousness). Data from a nationwide sample of 549 twin pairs collected through the MacArthur Foundation National Survey of Midlife Development in th...

The Keio Twin Research Center (KoTReC) was established in 2009 at Keio University to combine two longitudinal cohort projects — the Keio Twin Study (KTS) for adolescence and adulthood and the Tokyo Twin Cohort Project (ToTCoP) for infancy and childhood. KoTReC also conducted a two-time panel study of self-control and psychopathology in twin adolesc...

Background The phenotypic and aetiological architecture of depression symptomatology has been mostly studied in Western samples. In this study, we conducted a genetically informed factor analysis to elucidate both the phenotypic and aetiological architectures of self-reported depression among a Japanese adult twin sample. Methods Depressive sympto...

This study used a behavioral genetic approach to examine the genetic and environmental etiology of stability and changes in self-esteem in relation to personality. Multiple genetic analyses were conducted on a longitudinal dataset of self-esteem and Big Five personality scores among young adult Japanese twins over the course of a decade. There were...

The objective of this article is to measure the causal effect of education on earnings using a large dataset of twins compiled in Japan with wide-ranging socioeconomic information. Recent research conducted in China showed that, contrary to the case in Western countries, ability bias is large in estimating the return to education. It is argued that...

The present study examined: (1) gender and age differences of mean gender identity disorder (GID) trait scores in Japanese twins; (2) the validity of the prenatal hormone transfer theory, which predicts that, in dizygotic (DZ) twin pairs, twins with an opposite-gender co-twin more frequently exhibit GID traits than twins with a same-gender co-twin;...

Why does decision making differ among individuals? People sometimes make seemingly inconsistent decisions with lower expected (monetary) utility even when objective information of probabilities and reward are provided. It is noteworthy, however, that a certain proportion of people do not provide anomalous responses, choosing the alternatives with h...

Little is known about why people differ in their levels of academic motivation. This study explored the etiology of individual differences in enjoyment and self-perceived ability for several school subjects in nearly 13,000 twins aged 9–16 from 6 countries. The results showed a striking consistency across ages, school subjects, and cultures. Contra...

Since the pioneering work of Eaves and Eysenck (1974) appeared in Nature some 40 years ago, psychologists, sociologists, political scientists, and behavioral geneticists have investigated the effects of nature and nurture on the formation of social attitudes. It has consistently been found that manifestations of social attitudes (i.e., preferences,...

Prosociality is one of the most distinctive features of human beings but there are individual differences in cooperative behavior. Employing the twin method, we examined the heritability of cooperativeness and its outcomes on public goods games using a strategy method. In two experiments (Study 1 and Study 2), twin participants were asked to indica...

This study examined how the personality traits of behavioral inhibition and behavioral activation contribute to the development of anxiety and depression. We used two-wave short-term longitudinal data from 319 students. Data collections were two months apart. Personality traits were assessed using Gray's Reinforcement Sensitivity Theory: Behavioral...

Social inequality is a social phenomenon which varies across cultures. However, it does not only depend on social and cultural influences (e.g., public ideological opinion), but also on basic individual attitudes and values that promote socio-political decisions and behaviour. Behaviour genetic studies across several nations have found that individ...

Since the pioneering work of Eaves and Eysenck (1974) appeared in Nature some 40 years ago, psychologists, sociologists, political scientists, and behavioral geneticists have investigated the effects of nature and nurture on the formation of social attitudes. It has consistently been found that manifestations of social attitudes (i.e., preferences,...

This study reported results from interview survey to chief admission officers working for four selective universities in United States: Boston University, Brown University, Harvard University, and Pennsylvania State University. Findings were summarized in terms of admission policy, organization of admissions office, and admission processes. Charact...

Since the pioneering work of Eaves and Eysenck (1974), it has consistently been found that socio-political attitudes are genetically influenced. More recently, researchers have sought to clarify the nature of those genetic effects. In particular, they have examined the role of basic personality traits (Kandler et al. 2012; Verhulst et al. 2012). In...

A cultural behavior genetic approach was introduced as a prospective means to describe psychological differences between cultures. We compared genetic and environmental influences on remembered parenting for samples of twins from Japan and Sweden. Data were collected from 720 pairs of young adult Japanese twins and 824 pairs of adult Swedish twins...

The Keio Twin Research Center has conducted two longitudinal twin cohort projects and has collected three independent and anonymous twin data sets for studies of phenotypes related to psychological, socio-economic, and mental health factors. The Keio Twin Study has examined adolescent and adult cohorts, with a total of over 2,400 pairs of twins and...

Although growth in head circumference (HC) during infancy is known to predict later childhood outcomes, the mechanisms underlying this association with later sociocognitive abilities remain undetermined. Thus, using a sample of 241 pairs of normally developing Japanese twins, this study investigated the underpinnings of the association between HC g...

This study investigated the association between negative parenting (NP) and conduct problems (CP) in 6-year-old twins, taking into account the severity of hyperactivity/inattention problems (HIAP). Analyses of the data from 1,677 pairs of twins and their parents revealed that the shared environmental covariance between NP and CP was moderated by th...

Research has shown that personality traits have strong predictive validity for economic variables (e.g., income, work attainment) and epidemiological variables (e.g., longevity, physical health), as well as for psychological variables such as problem behaviors, and mental disorders. Importantly, personality traits are predictive even after controll...

Factors contributing to individual differences of empathy were examined using behavioral genetics methodology. Data related to individual levels of empathy and parental warmth received during childhood were collected from approximately 450 pairs of twins (ages 14-33). A bivariate model analysis clarified that shared family environmental factors did...

It has been reported that the ability to solve syllogisms is highly g-loaded. In the present study, using a self-administered shortened version of a syllogism-solving test, the BAROCO Short, we examined whether robust findings generated by previous research regarding IQ scores were also applicable to BAROCO Short scores. Five syllogism-solving prob...

The authors examined data (N = 34,108) on the differential reliability and validity of facet scales from the NEO Inventories. They evaluated the extent to which (a) psychometric properties of facet scales are generalizable across ages, cultures, and methods of measurement, and, (b) validity criteria are associated with different forms of reliabilit...

Direction of causation between the Gray’s Behavioral Inhibition System (BIS), depression, and anxiety was investigated. Data of 424 twin pairs were subjected to direction of causation modeling, which is a method for inferring causal relationship from cross-sectional family data. Four causal models were examined: (1) BIS influences depression/anxiet...

The present research examined the relationship between heritability and response time for the Big Five personality facets in three samples of adults and adolescents. We predicted that the larger the heritability of a facet the faster is the response to the items of that facet. In support of our predictions, the results showed that heritability and...

This study investigated the possible effects of genetic and environmental gender differences in effect on individual differences by using the Bem Sex Role Inventory (BSRI) with twins. A sex/gender-limitation analysis, a behavior genetics methodology was used to the following: (a) effects of gender-specific genes, (b) gender differences in quantitat...

Using a behavioral genetic approach, we examined the validity of the hypothesis concerning the singularity of human general intelligence, the g theory, by analyzing data from two tests: the first consisted of 100 syllogism problems and the second a full-scale intelligence test. The participants were 448 Japanese young adult twins (167 pairs of iden...

Gordon Allport (1937) has penned some of the most influential lines in the history of personality research. He defined personality as the “… dynamic organization within the individual of those psychophysical systems that determine his unique [sic] adjustments to this environment” (p. 48) and that “… personality is something and personality does som...

With the use of behavioral genetics methodology, in which variance of an observed trait can be decomposed into the effect of three latent variables, that is, genetic, shared environmental, and nonshared environmental, factors contributing to the formation of authoritarian conservatism were examined. 4111 participants （1279 male twins and 1899 femal...

Reports an error in "Substance and artifact in the higher-order factors of the Big Five" by Robert R. McCrae, Shinji Yamagata, Kerry L. Jang, Rainer Riemann, Juko Ando, Yutaka Ono, Alois Angleitner and Frank M. Spinath (Journal of Personality and Social Psychology, 2008[Aug], Vol 95[2], 442-455). In this article, an incorrect DOI was published. The...

Since natural selection produces genetically homogeneous populations with regard to adaptively important traits, the relatively high genetic variance associated with human personality is an enigma. In this article, we propose that humans adaptively control the activation of domain-specific mental mechanisms in accordance with personality. This proc...

Although there is a great deal of interest in the Behavioral Inhibition System (BIS) and Behavioral Activation System (BAS)—two temperaments formulated by Gray’s reinforcement sensitivity theory—few studies have examined the genetic and environmental etiology underlying their continuity and change. Using a two-wave longitudinal data set of twins fr...

People differ markedly in their risk for developing posttraumatic stress symptoms (PTSS) after exposure to traumatic events. Twin studies suggest that the trauma-PTSS relationship is moderated by genetic and environmental influences. The present study tested for specific types of genetic and environmental interaction effects on PTSS. A sample of 22...

The present study investigated the temperament model of Behavioral Inhibition/Activation Systems (BIS/BAS) conceptualized in Gray’s Reinforcement Sensitivity Theory with a Japanese sample. In Study 1, a Japanese version of BIS/BAS scales was developed and administered to 446 university students. Results showed that the BIS/BAS scales had sufficient...

The Tokyo Twin Cohort Project (ToTCoP) is a large-scale longitudinal study of 5 years based on 1619 pairs of infant twins reared together. The purpose of the study is to construct a population-based twin registry in Japan and to investigate human growth and development and twin themselves. It covers behavioral, neurological, physical and environmen...

This article introduced methodology of human behavior genetics and twin study, especially multivariate genetic analysis, which was then applied to examine association between temperament and problem behaviors among children aged four to six years old. A questionnaire was mailed to 142 mothers of twins to obtain mother ratings of children’s Effortfu...

There is empirical evidence that underlying the Big Five personality factors are two higher-order factors which have come to be known as “alpha” (α) and “beta” (β). The α factor is defined by the agreeableness, conscientiousness, and emotional stability domains; whereas β is delineated by extraversion and intellect. It has been argued that α and β...

This study developed Japanese version of Effortful Control (EC) scale for adults, and examined its reliability and validity. In Study 1, a questionnaire survey of 209 college and vocational school students showed sufficient internal consistency and test-retest reliability for the scale. Its correlational validity was also shown in terms of the rela...

We examined whether effortful control (EC), a temperament proposed by Rothbart and Bates (1998), has genetically coherent structure. A self-report measure of EC was administered to 450 Japanese twins (151 males and 299 females, ages 17 to 32 years) including 152 monozygotic and 73 dizygotic pairs. Univariate genetic analysis revealed that AE model...

Individual temperamental factors that contribute to the development of two perfectionism traits were studied in 428 Japanese undergraduate students using the Multidimensional Perfectionism Scale (MPS) and Temperament and Character Inventory (TCI). The results showed that self-oriented perfectionism is associated with the temperamental characteristi...

The multivariate genetic and environmental structure of Cloninger's Temperament and Character Inventory (TCI) was investigated in a sample of 617 pairs of adolescent and young adult twins from Japan. Additive genetic factors accounted for 22% to 49% of the variability on all TCI temperament scales. Although the theory predicts lower heritability fo...