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Biomedical subjects

A P Matheny

Publications and source records attributed to A P Matheny.

At least 37 records · Page 2Linked to original sources
PubMed1981

Behavioral contrasts in twinships: stability and patterns of differences in childhood.

Semistructured interviews with 305 mothers of same-sex twins were conducted periodically over the course of the twins' first 6 years. During each of the interviews, the mothers were asked to contrast the twins on a variety of specific behaviors. From the body of reports, 5 ages and 16 behaviors were selected for analysis as most illustrative of the main developmental trends for intrapair differences and similarities. For each of the behaviors, intrapair contrasts were moderately stable across age spans as long as 18-36 months. A set of behaviors related to negative aspects of temperament and a set of behaviors related to sociability were obtained at 6 months and were replicated at later ages. Concordance rates for the identical twin pairs were uniformly higher than for the fraternal pairs, suggesting that genotypic similarity was associated with intrapair similarity for aspects of emotionality and sociability.

Child↗
PubMed1980

Bayley's infant behavior record: behavioral components and twin analyses.

Factor analysis of 25 rating scales from Bayley's infant behavior record were performed for a sample of about 300-400 infant twins tested at 1 or more of the following ages: 3, 6, 9, 12, 18, and 24 months. The analysis provided 5 major factors and 2 minor factors that were considerably consistent at all ages. As defined by the scales with the strongest loadings, the major factors were denoted as task orientation, affect-extraversion, activity, auditory-visual awareness, and motor coordination, and the minor factors were denoted as kinds of mouthing behaviors. Further analyses by twin pairs generally provided higher concordance for identical pairs than for same-sex fraternal pairs, and the differences in concordance became more evident with an increase in age. Among the factors, task orientation showed the most persistent differences between identical and fraternal pairs. Profile analyses for all factors extracted at each age indicated that the profiles within identical pairs were more similar than profiles within fraternal pairs. Overall, the findings delineate some of the dimensions of temperament observed during testing and suggest that there are genetic influences on several behavioral characteristics and the organization of those characteristics during infancy.

Child Behavior↗
PubMed1979

Appraisal of parental bias in twin studies. Ascribed zygosity and IQ differences in twins.

A criticism of twin studies has been that the difference between the behavioral similarities of identical and fraternal twins is largely created by parental influences based on their perception of the twins' zygosity. This issue is examined for differences in the IQ scores found within pairs classified by parents and bloodtyping. The systematic differences in IQ scores could be attributed to zygosity classified by bloodtyping rather than by parental belief. The available evidence indicates that the twin method is still appropriate for human behavior genetics.

Blood Grouping and Crossmatching↗
PubMed1979

Hereditary determinants of manual torque.

Data from a longitudinal study of twin children and siblings, 155 girls and 134 boys (aged 4 to 9 yr.), on a torque test confirmed that during this age period manually produced circling patterns change from clockwise to counterclockwise orientation. A genetic influence is suggested.

Aging↗
PubMed1976

Relations between twins' similarity of appearance and behavioral similarity: testing an assumption.

Questionnaires rating twins' physical similarity and similarity of dress were obtained from the parents of 121 identical and 70 same-sex fraternal twin pairs. Within-pair difference scores on several behavioral measures (two intelligence tests, two perceptual tests, one reading test, one test of speech articulation, and one personality inventory) were correlated with the twins' scores for physical similarity and similarity of dress. The correlations revealed no systematic relation between the similarity of appearance and the similarity of behaviors for either the identical twin pairs or the same-sex fraternal twin pairs. The assumption that twins' behaviors are more alike because they are more similar in appearance does not seem warranted.

Body Height↗
PubMed1976

Retardation and twin concordance in infant mental development: a reassessment.

A reappraisal is made of Nichols and Broman's conclusion that there is no evidence that genetic influences are important in infant mental development if severely retarded twins are excluded from the sample. The reappraisal touches on certain idiosyncrasies of their sample, the test scores reported, and their definition of severe retardation. Data are presented for a sample of White twins who have been followed longitudinally since birth. For Bayley Mental Scale scores at 9 months of age, the monozygotic within-pair correlation was 0.85 and the dizygotic within-pair correlation was 0.62. With 13 retarded twins excluded, the correlations became 0.81 and 0.64, respectively, with the monozygotic correlation still being significantly larger (p less than 0.01). The present results indicate that genetic factors play a role in infant mental development.

Diseases in Twins↗
PubMed1976

Twins: within-pair similarity on Bayley's Infant Behavior Record.

Summary scores for behaviors rated on Bayley's Infant Behavior Record were obtained by summing sequential ratings for same-sex twins participating in a longitudinal study. The first year scores were based on visits made at 3, 6, 9, and 12 months, by 55 identical and 27 fraternal pairs; the second year scores were based on visits at 18, 24, and 30 months, by 47 identical and 27 fraternal pairs. During the first year, within-pair correlations for almost all behaviors were stronger for identical than for fraternal pairs; in the second year, within-pair correlations for identical twins were similar to those of fraternal twins except for the more cognitive behaviors. Composite scores were calculated for two behavioral clusters--one composed of behaviors related to Primary Cognition, and the other composed of behaviors related to Extraversion. Within-pair correlations were higher for identical than for fraternal twins in both the first and second years, indicating stronger and more consistent genetic influences on the more cognitive behaviors.

Age Factors↗
PubMed1976

Twins with academic learning problems: antecedent characteristics.

Developmental histories of 46 children experiencing academic difficulties, all of whom had participated since birth in a longitudinal study of twins, were compared with a matched control group of twins. Genetic influences on the liability for academic difficulties are suggested, since identical pairs were more likely than fraternal pairs to be concordant both for academic difficulties and for preschool behavioral characteristics specific to the index group.

Achievement↗
PubMed1975

Sex and genetic differences in hair color changes during early childhood.

Hair color was assessed routinely from three months to six years for children participating in a longitudinal study of twins: 169 female twin pairs, 161 male pairs, and 60 opposite-sex pairs. Age trends, established by sampling only one number of every pair, showed marked changes in hair color for both sexes, but there was a consistent excess of light-haired males and dark-haired females. Within-pair concordance rates were calculated for same-sex pairs whose zygosity had been determined independently through bloodtyping. A high rate of concordance was found for MZ twins at every age in spite of the general change in hair color, indicating a strong genetic influence in the timing of color changes. The results are discussed in terms of accelerated maturation of females, and the need for genetic models of the inheritance of hair color which are age- and sex-specific.

Age Factors↗
PubMed1975

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.

Age Factors↗
PubMed1975

Cognitive and personality factors associated with the double trapezium illusion.

76 pairs of 9- to 11-yr.-old twins (41 female, 35 male) who were discordant on the magnitude of error for the double trapezium illusion were given the Children's Personality Questionnaire and the Wechsler Intelligence Scale for Children (WISC). The Wilcoxon matched-pair signed-ranks test was used to determine whether the twins with relatively smaller magnitudes of error than their co-twins also manifested systematic differences on the personality factor scores and the WISC subtest scores. Among the female pairs, twins with smaller magnitudes of the illusion were relatively more stable (Factor C), more shrewd (Factor N), obtained higher scores on Similarities and Digit Span, and had longer reaction times before responding to the figures. Among the male pairs, similar trends were found but the differences were not as pronounced. The results are discussed in terms of Piaget's theory concerning children's deployment of attention and Kagan's reflective-impulsive dimension in children's cognitive judgments.

Child↗