Unconfounding the Confluence Model: A Test of Sibship Size and Birth-Order Effects on Intelligence

Few studies have examined birth order effects on personality in countries that are not Western, educated, industrialized, rich, and democratic (WEIRD). However, theories have generally suggested that interculturally universal family dynamics are the mechanism behind birth order effects, and prominent theories such as resource dilution would predict even stronger linear effects in poorer countries. Here, we examine a subset of up to 11 188 participants in the Indonesian Family Life Survey to investigate whether later–borns differ from earlier–borns in intelligence, educational attainment, Big Five, and risk aversion. Analyses were performed using within–family designs in mixed–effects models. In model comparisons, we tested for linear and non–linear birth order effects as well as for possible interactions of birth order and sibship size. Our estimated effect sizes are consistent with the emerging account of birth order as having relatively little impact on intelligence, Big Five, and risk aversion. We found a non–linear pattern for educational attainment that was not robust to imputation of missing data and not aligned with trends in WEIRD countries. Overall, the small birth order effects reported in other studies appear to be culturally specific. © 2020 The Authors. European Journal of Personality published by John Wiley & Sons Ltd on behalf of European Association of Personality Psychology

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A Tale of Two Variables: A Review of the Intellectual Consequences of Sibship Size and Birth Order

Review of Educational Research ◽

10.3102/00346543055003353 ◽

1985 ◽

Vol 55 (3) ◽

pp. 353-386 ◽

Cited By ~ 51

Author(s):

Lala Carr Steelman

Keyword(s):

Birth Order ◽

Intellectual Development ◽

Theoretical Explanation ◽

Future Research ◽

Sibship Size ◽

Academic Abilities ◽

Confluence Model ◽

Academic Consequences ◽

The Impact ◽

The Relationship

This paper critiques the literature on the relationship between sibling structure and academic abilities and achievement since Cicirelli’s (1978) earlier commentary on this topic. Assessed is the extent to which the confluence model, a theoretical explanation of the influence of sibling structure, fits the empirical observations made recently on the association between sibship structure and intellectual development. Since the studies reviewed in general tend to refute the confluence model, alternative interpretations of the impact of sibling structure on academic consequences are presented. Implications for future research are also provided.

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Effects of Birth Order on Intelligence, Educational Attainment, Personality, and Risk Aversion in an Indonesian Sample

10.31234/osf.io/5387k ◽

2018 ◽

Cited By ~ 1

Author(s):

Laura Botzet ◽

Julia Marie Rohrer ◽

Ruben C. Arslan

Keyword(s):

Risk Aversion ◽

Educational Attainment ◽

Birth Order ◽

Panel Study ◽

Effect Sizes ◽

Order Effects ◽

Sibship Size ◽

Resource Dilution ◽

Universal Family ◽

Intelligence Education

Few studies have examined birth order effects on personality in countries that are not Western, educated, industrialized, rich, and democratic (WEIRD), even though theories have generally suggested interculturally universal family dynamics as the mechanism behind birth order effects, and prominent theories such as resource dilution would even predict stronger effects in poorer countries. Here, we investigate a subset of up to 11,188 participants of the Indonesian Family Life Survey, an ongoing representative panel study, to study whether later-born siblings differ from earlier-borns in intelligence, educational attainment, personality, and risk aversion. Analyses were performed using within-family designs in mixed-effects models. In model comparisons we tested for linear and non-linear birth order effects as well as for possible interactions of birth order and sibship size. Our estimated effect sizes are consistent with the emerging account of birth order as having relatively little impact on intelligence, education, personality, and risk aversion; and they exclude recent estimates from WEIRD populations based on large sample sizes. Thus, even the small effects of birth order reported in other studies appear to be culturally specific.

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DamianSpengler_2020_EJP_Negligible Effects of Birth Order on Selection into Scientific and Artistic Careers, Creativity, and Status Attainment

10.31234/osf.io/2tnry ◽

2020 ◽

Author(s):

Rodica I. Damian ◽

Marion Spengler

Keyword(s):

Educational Attainment ◽

Personality Traits ◽

Birth Order ◽

Longitudinal Design ◽

Status Attainment ◽

Order Effects ◽

Occupational Prestige ◽

Career Outcomes ◽

Direct Effects ◽

Confluence Model

We tested birth order effects on selection into different careers (scientific, artistic, creative) and status attainment (educational attainment, occupational prestige, and income) using a large sample (n = 3,763), a longitudinal design, and relevant controls. Additionally, we tested mediation of birth order effects on career outcomes via personality traits, intelligence, and educational attainment. We found negligible birth order effects ranging from .02 to .12 on a correlational metric, where firstborns (vs. laterborns) selected into more creative careers and attained higher prestige and education. Conditional on the theoretically based mediation models tested, results showed that intelligence and educational attainment (but not personality traits) accounted for a statistically significant portion of the variance in the links between birth order and career outcomes. No direct effects of birth order on career outcomes remained when accounting for indirect effects through educational attainment. These findings bring modest support to the confluence model, no support to the niche-finding model, and suggest that one possible route via which birth order might impact career outcomes (if at all) could be via educational attainment.

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Birth Order Effects on Personality and Achievement Within Families

Psychological Science ◽

10.1111/1467-9280.00193 ◽

1999 ◽

Vol 10 (6) ◽

pp. 482-488 ◽

Cited By ~ 87

Author(s):

Delroy L. Paulhus ◽

Paul D. Trapnell ◽

David Chen

Keyword(s):

Birth Order ◽

Personality Development ◽

Family Data ◽

Order Effects ◽

Data Sets ◽

Confluence Model ◽

Wide Range ◽

Intellectual Achievement ◽

Personality Ratings ◽

Diverse Data

We investigated birth order effects on personality and achievement in four studies (N = 1,022 families) including both student and adult samples. Control over a wide range of variables was effected by collecting within-family data: Participants compared their siblings (and themselves) on a variety of personality and achievement dimensions. Across four diverse data sets, first-borns were nominated as most achieving and most conscientious. Later-borns were nominated as most rebellious, liberal, and agreeable. The same results obtained whether or not birth order was made salient (to activate stereotypes) during the personality ratings. Overall, the results support predictions from Sulloway's niche model of personality development, as well as Zajonc's confluence model of intellectual achievement.

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Mental Illness in Sibships of Two and Three

The British Journal of Psychiatry ◽

10.1192/bjp.119.552.481 ◽

1971 ◽

Vol 119 (552) ◽

pp. 481-487 ◽

Cited By ~ 34

Author(s):

John Birtchnell

Keyword(s):

Birth Order ◽

Population Control ◽

Control Group ◽

Order Effects ◽

Expected Number ◽

Sibship Size ◽

Birth Rank ◽

Large Numbers ◽

Sibling Position ◽

Population Control Group

A conspicuous deficiency of practically all birth order studies is the absence of a general population control group. Instead, a number of statistical methods of estimating the expected number of subjects in each sibling position have been used. These are based upon the assumption that for any given size of sibship there should be equal numbers of subjects in each birth rank. As Price and Hare (1969) have pointed out, there are a number of reasons why such as assumption is incorrect, and therefore why the conclusions based upon it are unreliable. Because, in most studies, only relatively small numbers of patients are available various methods of combining sibships of different sizes are adopted and the sexes of the siblings are ignored. To consider a sibling position irrespective of the size and composition of the sibship in which it occurs is unjustifiable. As birth order effects are relatively slight, large numbers of subjects are required to detect them. Unless a patient sample of several thousand is used the numbers in any sibship size are too small to permit analysis by birth rank. As sibship size is itself a possible variable, and as within each sibship the sexes of the siblings can be distributed in a variety of ways, birth order studies should ideally consider one sibship size at a time and should investigate sibling position by sex of sibling. Unfortunately, in sibships of four or more the numbers of combinations become so great as to render this approach impracticable.

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Negligible effects of birth order on selection into scientific and artistic careers, creativity, and status attainment

European Journal of Personality ◽

10.1177/0890207020969010 ◽

2020 ◽

pp. 089020702096901

Author(s):

Rodica Ioana Damian ◽

Marion Spengler

Keyword(s):

Educational Attainment ◽

Personality Traits ◽

Birth Order ◽

Longitudinal Design ◽

Status Attainment ◽

Order Effects ◽

Occupational Prestige ◽

Career Outcomes ◽

Direct Effects ◽

Confluence Model

We tested birth order effects on selection into different careers (scientific, artistic, and creative) and status attainment (educational attainment, occupational prestige, and income) using a large sample ( n = 3763), a longitudinal design, and relevant controls. Additionally, we tested mediation of birth order effects on career outcomes via personality traits, intelligence, and educational attainment. We found negligible birth order effects ranging from 0.02 to 0.12 on a correlational metric, where firstborns (vs. laterborns) selected into more creative careers and attained higher prestige and education. Conditional on the theoretically based mediation models tested, results showed that intelligence and educational attainment (but not personality traits) accounted for a statistically significant portion of the variance in the links between birth order and career outcomes. No direct effects of birth order on career outcomes remained when accounting for indirect effects through educational attainment. These findings bring modest support to the confluence model, no support to the niche-finding model, and suggest that one possible route via which birth order might impact career outcomes (if at all) could be via educational attainment.

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