Item responses to Digit Span and Letter-Number Sequencing were analyzed to develop a better-refined model of the two working memory tasks using the finite mixture (FM) modeling method. Models with ordinal latent traits were found to better account for the independent sources of the variability in the tasks than those with continuous traits, and…

This study investigated intellectual development in 4-7 years old Greek and Chinese children. They were examined on speeded performance, working memory, reasoning, and self-awareness tasks in order to investigate possible effects of learning the Chinese logographic system on possible differences in intellectual development between these ethnic…

This study investigated, in children aged 6-13 years, how different components of the working memory (WM) system (short-term storage and executive processes), within both verbal and visuospatial domains, relate to fluid intelligence. We also examined the degree of domain-specificity of the WM components as well as the differentiation of storage…

In this study, cross-cultural differences in cognitive test scores are hypothesized to depend on a test's cultural complexity (Cultural Complexity Hypothesis: CCH), here conceptualized as its content familiarity, rather than on its cognitive complexity (Spearman's Hypothesis: SH). The content familiarity of tests assessing short-term memory,…

In previous papers [Johnson, W., & Bouchard Jr., T. J. (2005a). Constructive Replication of the Visual-Perceptual-Image Rotation (VPR) Model in Thurstone's (1941) Battery of 60 Tests of Mental Ability. Intelligence, 33, 417-430.] [Johnson, W., & Bouchard Jr., T. J. (2005b). The Structure of Human Intelligence: It's Verbal, perceptual, and image…

Sex differences in spatial ability are well documented, but poorly understood. In order to see whether working memory is an important factor in these differences, 50 males and 50 females performed tests of three-dimensional mental rotation and spatial visualization, along with tests of spatial and verbal working memory. Substantial differences…

Empirical data suggest that there is at most a very small sex difference in general mental ability, but men clearly perform better on visuospatial tasks while women clearly perform better on tests of verbal usage and perceptual speed. In this study, we integrated these overall findings with predictions based on the Verbal-Perceptual-Rotation (VPR)…

Using 49 undergraduates, short-term memory (STM) spans, STM probe-recall tasks, and complex working memory (WM) spans were studied to assess the relationships among STM, WM, and verbal ability. Results indicate that STM and WM are separate cognitive constructs, and that both STM and WM are important to verbal abilities. (SLD)

Most psychometric tests of spatial ability are paper-and-pencil tasks at the ''figural'' scale of space, in that they involve inspecting, imagining or mentally transforming small shapes or manipulable objects. Environmental spatial tasks, such as wayfinding or learning the layout of a building or city, are carried out in larger spaces that…

Three experiments involving 85 learning-disabled (LD) children and 101 non-LD children investigated whether memory difficulties of LD children may be attributable in part to executive processing. Results suggest that LD readers may suffer from executive processing deficiencies, although they do not rule out effects of language-specific processes.…

The relation between individual differences in verbal ability and memory for order was investigated. Results indicated that (1) order and item information may be retained separately; (2) verbal ability is related to short-term recall but not recognition of order; and (3) transformation of order at output increases the relation. (Author/RD)

Measures of verbal intelligence and abstract reasoning were taken on a group of 31 college-aged and 32 elderly adults, together with mental-processing rates associated with choice reaction time, primary memory scanning, and lexical decoding. Group means showed that verbal IQ and lexical decoding were intact in the elderly subjects. (Author/LMO)

A conceptual theory for predicting the relations between intellectual abilities and performance during task practice is proposed and is evaluated through an experiment with high school and college students. This macro-theory integrates hierarchical theories of intellectual abilities with information-processing theories of automatic and controlled…

A multivariate hierarchical model of specific cognitive abilities was fitted to data from 196 adopted and 213 nonadopted children from the Colorado Adoption Project and 120 of their siblings to assess genetic influence on specific mental abilities. Genetic effects occur in middle childhood that differentially influence mental ability scores.…

Genetic involvement in specific verbal and spatial abilities and memory and perceptual speed was assessed using 163 adopted and 142 non-adopted 7-year-olds and their biological, adoptive, and non-adoptive parents. Results imply the existence of some genetic continuity from the early school years to adulthood for verbal and spatial abilities. (TJH)