Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Older children not smarter than their younger sibs, study finds

12.04.2006


A recent study provides some of the best evidence to date that birth order really doesn’t have an effect on intelligence.



The findings contradict many studies over the years that had reported that older children are generally smarter than their younger siblings.

This new study, based on a large, nationwide sample, suggests a critical flaw in that previous research, said Aaron Wichman, lead author of the new study and a teaching fellow in psychology at Ohio State University.


Most previous studies compared children from different families, so what they were finding were differences between large and small families, not differences between siblings, according to Wichman.

“Third- and fourth-born children all come from larger families, and larger families have disadvantages that will impact children’s intelligence,” he said.

“In reality, if you look at these larger families, the fourth-born child is just as intelligent as the first-born. But they all don’t do as well as children from a smaller family.”

Wichman conducted the study with Joseph Lee Rodgers of the University of Oklahoma and Robert MacCallum of the University of North Carolina–Chapel Hill and professor emeritus of psychology at Ohio State. Their findings were published in a recent issue of the journal Personality and Social Psychology Bulletin.

The new study used data involving nearly 3,000 families who participated in the National Longitudinal Survey of Youth, which is funded primarily by the U.S. Bureau of Labor Statistics. The NLSY is a nationally representative survey of people nationwide conducted by Ohio State’s Center for Human Resource Research.

The families in the study were followed over a long period of time. Data from this study were collected from 1986 through 1998. All the children in the study took intelligence tests that measured skill in mathematics, reading recognition and reading comprehension.

This data set allowed the researchers to compare children within a family, to see whether first-borns did better on these tests than did their younger siblings. There have been only a few other studies that have been done within families, and the results of those also suggested no link between birth order and intelligence.

But Wichman and his colleagues did something else to ensure a more accurate analysis: They compared intelligence test results at two specific age points (7-8 years old and 13-14 years old). Other studies had examined how children in a family scored on intelligence tests taken at one time, when children’s ages may vary widely. This may have affected study results.

Another key to this study was that researchers used a relatively new statistical technique, called multilevel modeling, that allowed them to separate two kinds of variation in intelligence: variation between families, and variation among siblings within families. In addition, this technique allowed the researchers to study variables such as environmental influences that might explain differences in intelligence.

In an initial analysis, the researchers examined the data while ignoring environmental influences on intelligence that differed between families. The results showed, as expected, that first-born children scored higher on intelligence tests than later-born children, and that as a child’s birth order increased, intelligence scores went down.

But then the researchers analyzed the data using a variable that could take into account environmental differences between families. That variable was the mother’s age at the birth of her first child.

“Mother’s age encapsulates many variables that could negatively effect the child-rearing environment. The younger a mother was at the birth of her first child, the lower we would expect intelligence scores to be within a family,” Wichman said.

That’s because younger mothers would tend to have less education, more children, lower income, and other factors that would negatively affect the intelligence of their children.

When the researchers controlled for mother’s age at first birth, the effect of birth order on intelligence was nearly eliminated.

So, by taking into account the mother’s age, the researchers were able to show that the reason that later-born siblings seem to have lower intelligence has to do with the fact that they come from larger families that may have different home environments than smaller families. It has little if anything to do with their birth order within the family, he said.

While the researchers used mother’s age at first birth to help control for differences between families, Wichman said other factors could have also been used instead. In fact, in an unpublished analysis, the researchers did use family size itself as a control variable, and found that it also nearly eliminated the link between birth order and intelligence.

However, using family size as the control variable can create other statistical errors, Wichman said, so the researchers used the mother’s age as a substitute.

The results, though, are clear, Wichman said.

“Birth order may appear to be associated with intelligence, but that’s only because larger families don’t have the advantages of smaller families,” he said. “When examined within families, there is no evidence of any significant association between birth order and intelligence. It’s not your birth order that is important – family environment and genetic influences are the really important factors.”

Aaron Wichman | EurekAlert!
Further information:
http://www.osu.edu

More articles from Studies and Analyses:

nachricht Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung

nachricht Scientists reveal source of human heartbeat in 3-D
07.08.2017 | University of Manchester

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>