Background: Brain morphology and physiological measures in schizophrenia have yielded inconsistent results. This may be due in part to difficulties in ascertaining precisely to what degree each measure deviates from its genetically and environmentally determined potential level. We attempted to surmount this problem in a paradigm involving…

Though many cognitive abilities exhibit marked decline over the adult years, individual differences in rates of change have been observed. In the current study, biometrical latent growth models were used to examine sources of variability for ability level (intercept) and change (linear and quadratic effects) for verbal, fluid, memory, and…

Recently a gene, termed EKN1, has been identified because of a chromosomal breakpoint that occurred in this gene. This chromosomal breakpoint was found in 4 family members that had specific reading disabilities (RDs), indicating that disruption of this gene may be contributing to the risk of developing RDs. This gene was further supported as…

Lower birth weight babies have worse outcomes, both short-run in terms of one year mortality rates and longer run in terms of educational attainment and earnings. However, recent research has called into question whether birth weight itself is important or whether it simply reflects other hard-to-measure characteristics. By applying within twin…

Do child development professionals have expectations about what it will be like to parent twins based on their professional experiences? Does their professional knowledge influence their approach to caregiving? And do their personal experiences as parents of twins change their research interests or how they work with children and families? To…

The incidence of twin births in the United States (US) has increased more than 65 per cent since 1980. However, the risk of injury to multiple-birth children is unknown. We sought to compare the risk of injury-related hospitalization and death between multiples and singletons. We conducted a retrospective cohort study using linked birth…

Findings of a series of studies on individual differences and maturational changes in expressivity at the neonatal stage and during early infancy are reported. Research results indicate that newborns are able to discriminate and imitate the basic emotional expressions: happy, sad, and surprised. Results show widened infant lips when the happy…

This paper presents the results of a study which examined heritability ratios for the major ethnic and socioeconomic groups in the Los Angeles Unified School District. Scores on three measures (the Cooperative Primary Reading Test, the Comprehensive Test of Basic Skills, and a composite set of intelligence tests) were compared for twins from…

This data compared language complexity measures, birth information, and family data for twins and singletons of the same sex, age, and socio-economic status. The subjects were four pairs of male twins, four pairs of female twins, four pairs of opposite sex twins, and 24 singletons, 32-33 months of age. Samples of each child's spontaneous…

A classification of natal influences is proposed with a model of their operation. Natal influences affect maternal capacity, maternal load, and maternal efficiency. Since maternal load is increased in twin pregnancy, results of twin studies must be generalized with caution. The method of co-twin control is exemplified by examination of a small…

This book examines the phonological development and impairment of Chinese-speaking children. It contains a series of studies of phonological acquisition and development of children in specific contexts (Putonghua or Modern Standard Chinese, the language variety promoted by the Chinese government, and normally developing children, children with…

Trend exhibited by the subjects of the present study was for men to show an earlier and more rapid decline than women, possibly as a reflection of their shorter life span. (Authors)

Reports results of an experiment involving a hydranencephalic infant lacking cerebral hemispheres and a normal twin in testing for associative learning. Cardiac orienting responses to stimulus omission indicated that learning had taken place in both infants. (CS)