PubMed Health⌕ Search

Biomedical subjects

F J van de Vijver

Publications and source records attributed to F J van de Vijver.

6 recordsLinked to original sources
PubMed2001

Personality in cultural context: methodological issues.

Methodological issues in cultural and cross-cultural personality research are described. A taxonomy of these studies is presented, based on whether a study is exploratory or tests hypotheses, and whether or not contextual information is measured. Core methodological issues are bias and equivalence: a taxonomy and a brief overview of statistical procedures to examine equivalence are presented, with a focus on procedures for assessing structural equivalence (i.e., similarity of meaning of an instrument across cultures). Examples are given of studies in which cultural and cross-cultural approaches, often seen as antithetical, have been fruitfully integrated. Finally, multilevel models are described in which personality characteristics are examined at individual and cultural level.

Cross-Cultural Comparison↗
PubMed2000

Signs of impaired cognitive function in adolescents with marginal cobalamin status.

BACKGROUND: Lack of cobalamin may lead to neurologic disorders, which have been reported in strict vegetarians. OBJECTIVE: The objective of this study was to investigate whether cognitive functioning is affected in adolescents (aged 10-16 y) with marginal cobalamin status as a result of being fed a macrobiotic diet up to an average age of 6 y. DESIGN: Data on dietary intake, psychological test performance, and biochemical variables of cobalamin status were collected from 48 adolescents who consumed macrobiotic (vegan type) diets up to the age of 6 y, subsequently followed by lactovegetarian or omnivorous diets, and from 24 subjects (aged 10-18 y) who were fed omnivorous diets from birth onward. Thirty-one subjects from the previously macrobiotic group were cobalamin deficient according to their plasma methylmalonic acid concentrations. Seventeen previously macrobiotic subjects and all control subjects had normal cobalamin status. RESULTS: The control subjects performed better on most psychological tests than did macrobiotic subjects with low or normal cobalamin status. A significant relation between test score and cobalamin deficiency (P: = 0.01) was observed for a test measuring fluid intelligence (correlation coefficient: -0.28; 95% CI: -0.48, -0.08). This effect became more pronounced (P: = 0.003) within the subgroup of macrobiotic subjects (correlation coefficient: -0.38; 95% CI: -0.62, - 0.14). CONCLUSION: Our data suggest that cobalamin deficiency, in the absence of hematologic signs, may lead to impaired cognitive performance in adolescents.

Adolescent↗
PubMed2000

Improved iodine status is associated with improved mental performance of schoolchildren in Benin.

BACKGROUND: An adequate iodine supply in utero and shortly after birth is known to be crucial to an individual's physical and mental development. The question of whether iodine supplementation later in life can exert a favorable influence on the mental performance of iodine-deficient populations was addressed in various studies, but with contradictory results. OBJECTIVE: The aim of this study was to examine the effect of an improvement in iodine status on mental and psychomotor performance of schoolchildren (7-11 y) who were moderately to severely iodine deficient. DESIGN: The study, which was originally planned as a double-blind, randomized, placebo-controlled intervention, was carried out in an iodine-deficient population of schoolchildren (n = 196) in northern Benin. As the population began to have access to iodized salt during the 1-y intervention period, the study population was split post hoc-on the basis of urinary iodine concentrations-into a group with improved iodine status and a group with unchanged iodine status. Changes in mental and psychomotor performance over the intervention period were compared. RESULTS: Children with increased urinary iodine concentrations had a significantly greater increase in performance on the combination of mental tests than did the group with no change in urinary iodine concentrations. CONCLUSIONS: An improvement in iodine status, rather than iodine status itself, determined mental performance in this population, which was initially iodine deficient. These findings suggest a "catch-up" effect in terms of mental performance.

Benin↗
PubMed1993

A simple test of the Law of Initial Values.

The conceptualization and testing of the Law of Initial Values remains a controversial issue. We critically review common procedures to test the Law, and a simple test of the Law is described and illustrated. The reduction of variance from the pretest to the posttest is crucial in this test.

Heart Rate↗