A brief discussion of theories of general intelligence precedes a report of relevant empirical data. Results from the factor analysis of more than 20 sets of Wechsler Adult Intelligence Scale (WAIS) data indicate that the WAIS clearly is not a one-factor scale. It does not measure a single, general intelligence. Roughly 17 percent of the reliable…

Selective subject attrition from longitudinal study panels can bias estimates of developmental change. Particularly in studies of older adults, sampling effects can adversely affect attempts to estimate true ontogenetic change. Selective attrition effects were examined in 636 Pennsylvania adults (138 males, 498 females), aged 58-91, who were…

The term "statistical significance" is often misunderstood or abused to imply a large effect size. A recent example is in the work of J. P. Rushton (1988, 1990) on differences between Negroids and Caucasoids. Rushton used brain size and cranial size as indicators of intelligence, using Pearson "r"s ranging from 0.03 to 0.35.…

This paper criticizes Zajonc's confluence model of the relationship between sibling spacing and sibling intelligence. According to Zajonc, variations in the intellectual performance of individuals are accounted for in part by two features of the individual's family of orientation: (1) the number of children in that family, and (2) the spacing…

This paper reports survey results, from a sample of 76 women past child bearing age with varying numbers of offspring, which suggest that not only sibling absence but also distinctive characteristics of mothers would be considered in studies of the personal and social characteristics of only children. (Among the maternal characteristics mentioned…

This paper describes a study that examined the possibility that there is more than one category of only children. The study attempted to resolve inconsistencies in previous research outcomes with only children. The study involved data from female only children who were assessed longitudinally from early adolescence to late middle age on the…

The interest of the psychologist in bilingualism from its origins in the early 1900's to the present is traced. Bilingualism and intelligence are discussed as well as some recent studies on bilingualism and cognitive development. Several areas where psychologists may provide valuable insights into the process of becoming bilingual are discussed…