Children''s Behavioral Inhibition Over Age and Across Situations: Genetic Similarity for α Trait During Change

Ratings of behaviors pertaining to inhibition were observed for 130 twins participating in a longitudinal study. Ratings were available for four ages (12, 18, 24, and 30 months) and from three sources at each age: direct observations obtained in a laboratory setting, direct observations obtained in conjunction with infant mental testing, and a temperament measure from a questionnaire completed by parents. For the individual twins, the age-to-age correlations were in the moderate range (.26 to .64). The situation-to-situation correlations were generally in the same range (.17 to .64). When the twins were recombined into twin pairs, within-pair (intraclass) correlations indicated that monozygotic (MZ) twins were more concordant than dizygotic (DZ) twins for each of the behaviors at each of the ages. Also, the MZ twins were more concordant for the direction and degree of behavioral change from age to age or from situation to situation. These data provide additional evidence for the biological influence on behavioral inhibition, a characteristic that has been studied in temperament and personality research. The results suggest that the trait of behavioral inhibition and a change in the trait are genetically conditioned. In addition, it is suggested that the concept of trait be expanded to include the person-centered biological regulation of change.     

ABILITIES OF TWINS

The investigation concerns two main problems: (1) the distribution of ability test scores among twins in comparison with single-borns; and (2) intra-pair similarity among the various twin categories. More than 1000 individual twins were compared with 2700 single-borns on 21 test variables covering Swedish, Mathematics and English. The twin group consistently showed a lower average than the single-borns due to a displacement of the test score distribution as a whole among twins. The intra-pair similarities, expressed as intra-class correlations, run between 0.85 and 0.90 for identical pairs, whereas like-sex fraternals showed coefficients about 0.60. The unlike-sex fraternals had coefficients ten to twenty hundredths lower than those of the like-sex pairs.     

Left-handedness in twin families: support of an environmental hypothesis

Information on handedness, assessed as writing-hand, was collected from 197 MZ twin pairs and 203 DZ twin pairs and from their parents, spouses, and children. Associations for pairs of relatives were studied by 2 X 2 tables, computing chi squared-values and tetrachoric correlations. Correlations of about .3 were obtained for mother-offspring and sibling pairs, while for cousins the correlation was .25 (in a small sample). No other significant associations were found, not even for twins. These results suggest only a small, if any, genetic effect, and only a small environmental between family effect, most of which seems to be a maternal effect. The lack of cotwin correlations and correlations for one of the twins with her/his ordinary brothers/sisters suggest the existence of an effect specific to twins, since the correlation for pairs of ordinary siblings is significant. Conclusions drawn from twin studies alone may be biased. The frequency of left-hand writers has increased from 1% to 10% in the different age groups born during the last century in Norway. This age effect is present mainly in hand writing and not so much in handedness generally, suggesting a decrease in cultural repression against left-hand writing.     

Relations between CBM (oral reading and maze) and reading comprehension on state achievement tests: A meta-analysis

The purpose of this study was to examine the validity of two widely used Curriculum-Based Measures (CBM) in reading—oral reading and maze—in relation to reading comprehension on state tests using a meta-analysis. A total of 61 studies (132 correlations) were identified across Grades 1 to 10. A random-effects meta-analysis was conducted to estimate the average correlations between the two CBM tasks and reading comprehension on state tests, and to analyze the effects of potential moderating variables (characteristics of study, students, CBM, and state tests). Results revealed that the average correlation for oral reading was significantly larger than that for maze when all grade levels were included together in the analysis. When grade levels were separated, the difference between average correlations was only at the higher grades (Grades 4–10), favoring oral reading. In terms of correlations by grade level, oral reading and maze showed a similar pattern; that is, correlations were comparable across elementary grades, but decreased for secondary grades. In addition to the type of CBM and grade level differences, type of publication, type of state tests (commercial versus state-developed), and time interval between CBM and state tests were significant sources of variance in correlations. Implications for research and educational practice are discussed highlighting the somewhat different conclusions from previous literature, especially regarding the use of CBM for older students.     

Reliability and validity of retrospective self-reports of the age of pubertal onset using twin, sibling, and college student data

This study presents a methodology, derived from behavioral genetic research, designed to evaluate the validity of retrospective self-report inventories. The application of this technique to college student, twin, and sibling data demonstrated the reliability and validity of a retrospective self-report questionnaire on the timing of pubertal onset. Support was provided by four main findings: (1) substantial test-retest reliability coefficients for individual items (r ranged from .73 to .97) were obtained for a sample of college students; (2) nearly all of the monozygotic twin (MZ) intraclass correlations exceeded those for dizygotic twins (DZ); (3) the magnitude of the test-retest and intraclass correlations for recall of the timing of pubertal onset followed theoretical expectations for a trait demonstrating significant genetic influence (i.e., r for the same individual tested twice greater than r for MZs greater than r for DZs greater than r for siblings); (4) the expected secular trend of a cross-generational decrease in the age of sexual maturation was demonstrated for retrospective self-reports of family members representing three different generations. Moreover, the size of the mean differences across generations mirrored those reported for nonretrospective assessments of the actual age of pubertal onset. Finally, the value of retrospective self-report surveys in psychological research is discussed, and the relative merits of these instruments as indices of individual differences in pubertal development, as opposed to indices of the actual age of sexual maturation, are emphasized.     

Intelligence test scores from infancy to adulthood for a craniopagus twin pair neurosurgically separated at 4 months of age

Long-term effects in a neurosurgically separated twin pair were illuminated by standard psychological test scores obtained over a period from 2 to 38 years of age. Interdigitation of the gyri of their right frontal lobes had necessitated separation in two stages at 4 months of age. One twin clearly suffered some brain injury and showed some impairment during the testing at 5 years of age. The scores of both twins rose at the adult testing. The brighter twin has an IQ comparable to that of the mother. The unique data set is a kind of model for long-term assessment of early brain surgery, particularly with craniopagus twins.     

Relationships among selected perceptual-motor tests and teachers' rankings as a function of children's age and sex

28 third grade (M = 8.4 yr.) and 28 sixth grade (M = 11.8 yr.) children were administered the Body Coordination Test and Gross Motor Skill Test to assess the relationship between these measures as a function of age, sex, and the subjective ratings (ranks) of their physical education teacher. Scores were significantly correlated (.76) for all as were scores within each grade and sex. The teachers' subjective ranking of younger subjects on their general physical performance was significantly related to scores on both tests but only moderately related to general coordination and unrelated to somatic development. Significant correlations were observed for the older subjects for all ranks on the Gross Motor Skill Test but were only moderately related or unrelated on the Body Coordination Test. These tests may have utility in evaluating motor developmental differences among children.     

Twins' reactions to delayed auditory feedback

10 pairs of identical and 10 pairs of fraternal twins, matched by age, spoke under conditions of 0.0-, 100-, 200-, 300-, 400-, and 500-msec. delayed auditory feedback. Length of spoken passages was controlled. Product-moment and intraclass correlations were calculated for speaking times and disfluencies. Significant Pearson rs for times were noted at 0.0 and 300 msec. for both groups and at 100, 200, and 400 msec. for identical twins, while fraternal twins' times were significantly correlated at 500 msec. Difference scores were significantly correlated at 100, 200, 300, and 400 msec. for identical twins. Disfluencies were significantly correlated for identical twins at 400 msec. Data were combined with those of Timmons' (1969) study, increasing subjects to 21 pairs per group. Intraclass correlations supported the contention that responses of identical twin pairs to delayed auditory feedback were more highly correlated than those for fraternal twin pairs.     

Literacy acquisition influences children's rapid automatized naming

Previous research has established that learning to read improves children's performance on reading‐related phonological tasks, including phoneme awareness (PA) and nonword repetition. Few studies have investigated whether literacy acquisition also promotes children's rapid automatized naming (RAN). We tested the hypothesis that literacy acquisition should influence RAN in an international, longitudinal population sample of twins. Cross‐lagged path models evaluated the relationships among literacy, PA, and RAN across four time points from pre‐kindergarten through grade 4. Consistent with previous research, literacy showed bidirectional relationships with reading‐related oral language skills. We found novel evidence for an effect of earlier literacy on later RAN, which was most evident in children at early phases of literacy development. In contrast, the influence of earlier RAN on later literacy was predominant among older children. These findings imply that the association between these two related skills is moderated by development. Implications for models of reading development and for dyslexia research are discussed.     

Patterns of Mother-Infant Contact: The Significance of Lateral Preference

The use of assisted reproductive technology is increasing rapidly. Research, although sparse, has resulted in inconsistent findings as to the developmental prognosis for infants conceived by assisted reproductive techniques such as in vitro fertilization and the use of fertility drugs. In the present study, the authors compared twins who were spontaneously conceived with those who were conceived through assisted reproductive technology. The authors found differences in birth weight and gestational age. Infants conceived by assisted reproductive technology fared worse than did those who were spontaneously conceived. The authors found no differences between the groups in mental development at 24 months of age, but they found evidence of differences in physical development. Implications of the findings are discussed.     

Assisted reproduction versus spontaneous conception: a comparison of the developmental outcomes in twins

The use of assisted reproductive technology is increasing rapidly. Research, although sparse, has resulted in inconsistent findings as to the developmental prognosis for infants conceived by assisted reproductive techniques such as in vitro fertilization and the use of fertility drugs. In the present study, the authors compared twins who were spontaneously conceived with those who were conceived through assisted reproductive technology. The authors found differences in birth weight and gestational age. Infants conceived by assisted reproductive technology fared worse than did those who were spontaneously conceived. The authors found no differences between the groups in mental development at 24 months of age, but they found evidence of differences in physical development. Implications of the findings are discussed.     

Maternal speech style with prelinguistic twin infants

The mother–infant communicative speech of a group of mothers of 4‐month‐old first‐born twin infants was compared to the speech of a group of mothers of first‐born singleton infants. Maternal groups were matched on age, education level, mother–infant attachment status and infant gender, and maternal depression was assessed as a control variable. Maternal speech was coded for focus, content, complexity and syntax of mothers' utterances. The findings of earlier studies with toddler age twins, that maternal speech style was more directive and less infant‐focused, were replicated in this prelinguistic period of infancy. Compared to mothers of singletons, mothers of twins used less infant‐focused speech, were less responsive to their infants' cues, and attributed less agency to their infants. Mothers of twins also used fewer questions and requests but did not differ from mothers of singletons in their use of negatives and imperatives. These early differences in the language learning environments of twin and singleton infants may be due to the reduced opportunities that mothers of twins have to establish dyadic communicative routines with their infants and to familiarize themselves with their infants as interactive partners, and may have implications for the early language development of twins. Copyright © 2002 John Wiley & Sons, Ltd.     

Anatomical correlates of normal and impaired language in a set of dizygotic twins

This report presents findings for a set of dizygotic twins at age 4 years 9 months. The male was diagnosed as specifically language impaired. For both children, the left-right perisylvian configuration was atypical. Only the male's configuration was symmetrical, a finding in line with autopsy data reported for subjects with "developmental dyslexia" who also may have had a form of language impairment. In addition, the male had an atypical (L greater than R) configuration of the cerebral hemispheres, a finding not seen in his twin, or in a series of volunteers without a history of developmental language impairment. The in utero effects of gonadal hormones that may account for these findings are discussed.     

Persons, situations, and time: a genetic view of behavioral change in children.

Twin children participating in a longitudinal study were observed at 9, 12, 18, 24, and 30 months of age in two settings: unstructured free play and relatively structured test taking. Behaviors relating to adaptability to the two settings were rated and the scores analyzed for evidence of continuity both across settings and across ages. Age-to-age correlations for the adaptability scores for each setting yielded a simplex pattern of low-moderate order. Correlations of individuals' scores across settings were also of low-moderate order. Within-pair correlations indicated that identical twins were more similar that same-sex fraternal twins in both settings, but correlations were consistently stronger in the playroom setting. Analysis of variance was performed to test for within-pair concordance in the direction and degree of change. Identical pairs remained significantly more similar in adaptability from one setting to another even when change in adaptability occurred. Similar results were found for change across ages; however, these differences were significant only in the playroom setting. Results suggest that situation variables contribute to the low stabilities frequently reported for personality dimensions but that the direction and degree of behavioral change are genetically conditioned.     

Separated twins and the genetics of personality differences: a critique

This article discusses studies of separated twins, with special emphasis on the Minnesota Study of Twins Reared Apart (MISTRA), to determine whether they support the existence of an important genetic component in behavioral and personality differences. The methods and conclusions of the MISTRA team are discussed in the context of earlier studies of separated identical twins. I argue that volunteer-based studies are biased toward greater twin similarity. In addition, the MISTRA research team did not publish or share raw data and case history information. Reared-together and reared-apart monozygotic twins share important environmental similarities not controlled for by comparing personality correlations. I propose an alternative control group consisting of biologically unrelated pairs of strangers matched on all environmental factors common to pairs of separated monozygotic twins. I conclude that the evidence from studies of twins reared apart does not support the role of genetic factors in personality and behavioral differences.     

Importance of shared genes and shared environments for symptoms of depression in older adults.

The Center for Epidemiologic Studies-Depression scale was administered to 68 identical and 161 fraternal twin pairs reared apart and 114 identical and 138 fraternal pairs reared together to ascertain relative genetic and environmental contributions to individual differences in self-reported depressive symptoms. Intraclass correlations and model fitting indicated that genetic influences explained 16% of the variance in total depression scores and 19% for the Psychomotor Retardation and Somatic Complaints subscale, but heritability was minimal for the Depressed Mood and Well-Being subscales. Influence of family rearing context played a substantial role in explaining twin similarity, whereas unique life experiences accounted for the greatest proportion of variance. Significant age group differences were observed, with heritability greater in twins of 60 years of age or older than in twins under 60, especially for Psychomotor Retardation.     

Genetic influence on life events during the last half of the life span

Genetic influence on perceptions of major events later in life was assessed with a combination of twin and adoption designs as part of the Swedish Adoption/Twin Study of Aging (SATSA). The SATSA design includes 4 groups totaling 399 pairs of same-sex twins: identical and fraternal twins reared apart and matched twins reared together. The average age of the twins was 59 years. The results demonstrate significant genetic influence on reports of the occurrence of life events, especially for controllable events in which the individual can play an active role. Maximum likelihood model-fitting estimates of genetic influence indicate that 40% of the variance of the total life events score is due to genetic differences among individuals. How genetic factors can affect life experiences and directions for future research are discussed.     

Development of a rating scale to measure social skills in children: The matson evaluation of social skills with youngsters (MESSY)

The development of a scale for assessing social skills with children is reported. The Matson Evaluation of Social Skills with Youngsters (MESSY) was completed on 744 children between 4 and 18 years of age. A self-report form was completed on 422 children while 322 children were rated on a teacher-report measure using a 5-point Likert-type scale. Analyses included test-retest reliability conducted at a 2-week interval using Pearson correlations, factor-analytic procedures and selected analyses of variance and appropriate post-hoc tests. Implications of present findings and directions for future research are discussed.     

The correlational validity of IQ as a function of ethnicity and desegregation

IQ tests were viewed solely as predictors in this investigation. It was printed out that there is little or no data to support the prevalent assumptions that IQ tests predict school performance equally well for different ethnic groups and/or in a desegregated school setting. Moreover, test users and publishers often mistakenly imply or assume that the correlational validity for a total ethnically heterogeneous population applies in equal magnitude to the respective ethnic subgroups of that population. An investigation to provide evidence relevant to these assumptions was conducted using all the pupils in grade K-3 in Berkeley, California—the first large district to voluntarily desegregate its schools completely.

The results revealed equal but very low within-ethnic-group correlations between IQ and achievement measures administered concurrently prior to desegregation and for tests administered one and two years following desegregation. The correlations between IQ and the criteria for the ethnic groups were, as expected, significantly lower than the total population correlation. The practical implications of these findings of generally poor predictability were discussed.     

对中学超常儿童的教育实验——北京八中首届超常实验班追踪研究

为期四年的超常儿童的教育实验,详细考察了超常儿童在特殊班级教育条件下的学习潜力、认知和个性发展及身体发育等情况。结果显示,这种教育形式既适应了超常儿童较大的学习潜力,促进了他们认知的进一步发展,激发了他们积极的个性特征,而且身体发育良好。从而证明,特殊班级的集体教育对中学阶段的超常儿童是一种有效的教育形式。