scholarly journals The secular trend of intelligence test scores: The Danish experience for young men born between 1940 and 2000

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261117
Author(s):  
Emilie R. Hegelund ◽  
Thomas W. Teasdale ◽  
Gunhild T. Okholm ◽  
Merete Osler ◽  
Thorkild I. A. Sørensen ◽  
...  
Keyword(s):  
Nutrition Education ◽  
Birth Cohort ◽  
Family Size ◽  
Test Scores ◽  
Secular Trend ◽  
Young Men ◽  
Intelligence Test ◽  
Birth Cohorts ◽  
Intelligence Test Scores ◽  
Secular Increase

The present study investigated the Danish secular trend of intelligence test scores among young men born between 1940 and 2000, as well as the possible associations of birth cohort changes in family size, nutrition, education, and intelligence test score variability with the increasing secular trend. The study population included all men born from 1940 to 2000 who appeared before a draft board before 2020 (N = 1,556,770). At the mandatory draft board examination, the approximately 19-year-old men underwent a medical examination and an intelligence test. In the statistical analyses, the IQ mean and standard deviation (SD) were estimated separately for each of the included annual birth cohorts based on information from birth cohorts with available total intelligence test scores for all tested individuals (i.e. 1940–1958 and 1987–2000; the mean and SD were interpolated for the intermediate birth cohorts). Moreover, the possible associations with birth cohort changes in family size, height as a proxy for nutritional status, education, and IQ variability were investigated among those birth cohorts for whom a secular increase in intelligence test scores was found. The results showed that the estimated mean IQ score increased from a baseline set to 100 (SD: 15) among individuals born in 1940 to 108.9 (SD: 12.2) among individuals born in 1980, since when it has decreased. Focusing on the birth cohorts of 1940–1980, for whom a secular increase in intelligence test scores was found, birth cohort changes in family size, height, and education explained large proportions of the birth cohort variance in mean intelligence test scores, suggesting that these factors may be important contributors to the observed Flynn effect in Denmark.

The secular trend of intelligence test scores in the present century: The Danish experience

Intelligence ◽  
2021 ◽  
Vol 85 ◽  
pp. 101525
Author(s):  
Emilie R. Hegelund ◽  
Gunhild T. Okholm ◽  
Thomas W. Teasdale
Keyword(s):  
Test Scores ◽  
Secular Trend ◽  
Intelligence Test ◽  
Danish Experience ◽  
Intelligence Test Scores

Maternal Age and Children's Ability

1978 ◽  
Vol 47 (3) ◽  
pp. 815-818 ◽  
Author(s):  
Patricia Zybert ◽  
Zena Stein ◽  
Lillian Belmont
Keyword(s):  
Social Class ◽  
The Netherlands ◽  
Birth Order ◽  
Test Scores ◽  
Maternal Age ◽  
Young Men ◽  
Intelligence Test ◽  
Spacing Interval ◽  
Intelligence Test Scores ◽  
Age At Birth

Associations of maternal age at birth and subsequent intelligence test scores of children were examined in a series of over 1500 young men from the Netherlands. All subjects were members of 2-child families and were resident in Amsterdam at age 19 yr. Possible confounding by birth order, spacing interval, social class and sex of sibling were considered. Significant correlations between maternal age and child's ability remained in three of the four possible birth order/social class combinations.

Understanding Terminal Decline in Cognition and Risk of Death

2006 ◽  
Vol 11 (3) ◽  
pp. 164-171 ◽  
Author(s):  
Patrick Rabbitt ◽  
Mary Lunn ◽  
Danny Wong
Keyword(s):  
Risk Factors ◽  
Longitudinal Study ◽  
Test Scores ◽  
Intelligence Test ◽  
Practice Effects ◽  
Risk Of Death ◽  
Risk Of Mortality ◽  
Impending Death ◽  
Intelligence Test Scores ◽  
Reduced Risk

There is new empirical evidence that the effects of impending death on cognition have been miscalculated because of neglect of the incidence of dropout and of practice gains during longitudinal studies. When these are taken into consideration, amounts and rates of cognitive declines preceding death and dropout are seen to be almost identical, and participants aged 49 to 93 years who neither dropout nor die show little or no decline during a 20-year longitudinal study. Practice effects are theoretically informative. Positive gains are greater for young and more intelligent participants and at all levels of intelligence and durations of practice; declines in scores of 10% or more between successive quadrennial test sessions are risk factors for mortality. Higher baseline intelligence test scores are also associated with reduced risk of mortality, even when demographics and socioeconomic advantage have been taken into consideration.

The Effects of Repeated Retesting: III. Further Experiments and General Conclusions

1950 ◽  
Vol 2 (4) ◽  
pp. 182-197 ◽  
Author(s):  
V. R. Cane ◽  
A. W. Heim
Keyword(s):  
Test Scores ◽  
Technical College ◽  
Intelligence Test ◽  
Repeated Testing ◽  
Short Term ◽  
The Third ◽  
Joint Interpretation ◽  
Unselected Population ◽  
Intelligence Test Scores ◽  
Technical College Students

This is the third of a series of papers dealing with the effects of repeated retesting on intelligence test scores. It comprises an account of two further experiments, and a discussion of the four so far performed, since each throws light on the results of the others and it is their joint interpretation which is thought to be of value. The two earlier experiments consisted in repeated testing of a group of W.E.A. students and a group of mentally defective boys by an intelligence test (AH 4) designed for an unselected population. In the two later experiments, a group of Technical College students and a group of Naval Ratings were repeatedly tested on another intelligence test (AH 5), designed for a population of high-grade intelligence, such as university students. Examination of all the results confirms the artificiality of the “ceiling effect” which was suspected in the first experiment; it suggests that, given sufficient scope, subjects of all levels of intelligence would, with repeated trials on the same test, continue to improve their score up to and beyond 10 testing; and that, given comparable opportunity, subjects with initially higher scores will tend to improve more than those with initially lower scores. All these results concern short-term experiments with testing at weekly intervals. The four sets of results considered jointly indicate that conclusions on these problems should be drawn only in terms of the relation between the level of the test and that of the group tested: this offers some resolution of the conflicting findings of earlier investigators.

Neonatal Hyperbilirubinemia and Physical and Cognitive Performance at 17 Years of Age

PEDIATRICS ◽  
1991 ◽  
Vol 88 (4) ◽  
pp. 828-833
Author(s):  
Daniel S. Seidman ◽  
Ido Paz ◽  
David K. Stevenson ◽  
Arie Laor ◽  
Yehuda L. Danon ◽  
...  
Keyword(s):  
Test Scores ◽  
Serum Bilirubin ◽  
School Achievement ◽  
Ethnic Origin ◽  
Full Term ◽  
Neonatal Hyperbilirubinemia ◽  
Intelligence Test ◽  
Coombs Test ◽  
Intelligence Test Scores ◽  
The Military

To estimate the effect of neonatal hyperbilirubinemia on long-term cognitive ability in full-term newborns with a negative Coombs test, we performed a 17-year historical prospective study of 1948 subjects. Intelligence tests and medical examinations performed at the military draft board were stratified according to serum bilirubin concentration. A logistic regression analysis was used to adjust for the confounding effects of gestational age, birth weight, Apgar score, ethnic origin, socioeconomic class, paternal education, birth order, and the administration of phototherapy and exchange transfusion. No direct linear association was shown between neonatal bilirubin levels and intelligence test scores or school achievement at 17 years of age. However, the risk for low intelligence test scores (IQ score <85) was found to be significantly higher (P = .014) among full-term male subjects with serum bilirubin levels above 342 µmol/L (20 mg/dL) (odds ratio, 2.96; 95% confidence interval, 1.29-6.79). This association was not observed among female subjects. We conclude that severe neonatal hyperbilirubinemia, among full-term male newborns with a negative Coombs test, could be associated with lower IQ scores at 17 years of age.

INFLUENCE OF SODIUM AMYTAL ON INTELLIGENCE-TEST SCORES

The Lancet ◽  
1942 ◽  
Vol 239 (6197) ◽  
pp. 676-677 ◽  
Author(s):  
Patrick Slater ◽  
William Sargant ◽  
Margaret Glen
Keyword(s):  
Test Scores ◽  
Intelligence Test ◽  
Intelligence Test Scores
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