Elsevier

Intelligence

Volume 92, May–June 2022, 101651
Intelligence

The sexes do not differ in general intelligence, but they do in some specifics

https://doi.org/10.1016/j.intell.2022.101651Get rights and content

Highlights

  • Despite no differences in general intelligence, there are sex differences in specific abilities.

  • Reliable and meaningful female advantages are found in processing speed and writing.

  • Reliable and meaningful male advantages are found in visual processing.

  • Sex differences research should consider construct breadth and moving beyond mean differences only.

Abstract

Reliable and meaningful sex differences exist in specific cognitive abilities despite no reliable or meaningful sex difference in general intelligence. Here we use Cattell-Horn-Carroll (CHC) theory to highlight research findings related to sex differences in intelligence, with a focus on studies of test scores from comprehensive intelligence measures that were obtained from large and representative samples of children and adolescents. Female advantages in latent processing speed and male advantages in latent visual processing are the most meaningful and consistently reported sex differences regarding CHC broad cognitive abilities. Differences have been reported in narrow and specific ability constructs such as mental rotation and object memory location. In academic achievement, the largest and most consistent findings are female advantages in writing, whereas male advantages at higher math ability levels are also found. Empirical descriptions of sex differences should consider the breadth of the construct under study and incorporate analysis beyond simple mean differences. Score analysis methods that utilize multiple-group confirmatory factor models and multiple-indicator multiple cause models are useful to address the former, and analysis methods such as quantile regression and male-female ratio calculations along score distributions are useful to address the latter. An understanding of why specific ability differences exist in combination and in the presence of similarities will improve researchers' understanding of human cognition and educational achievements.

Introduction

The study of sex differences in psychological variables dates back over 100 years (Hedges & Nowell, 1995; Maccoby & Jacklin, 1974; Woolley, 1914).1 Research findings are sometimes misunderstood. Generalizations from those findings are provocative (Ceci & Williams, 2007). Because most effect sizes used to quantify mean sex differences in psychological variables are described as either non-existent or “small,” the Gender Similarities Hypothesis has been promoted to replace a “differences” hypothesis (GSH; Hyde, 2005, Hyde, 2014).2

The GSH applies to intelligence and academic achievement variables, broadly speaking. The sexes are similar in general intelligence (Jensen, 1998); however, consistent differences emerge in some specific abilities (Reynolds, Scheiber, Hajovsky, Schwartz, & Kaufman, 2015; Zell, Krizan, & Teeter, 2015). If there is no sex difference in general intelligence, is it worth studying sex differences in specific abilities? We think the answer is yes (cf. Archer, 2019; Hyde, 2014). Findings may shed light on human cognition and have implications for understanding educational progress and achievements. In this commentary we highlight sex differences in specific abilities, especially from findings related to broad cognitive abilities, discuss important matters in such research, and provide suggestions for future research. We focus on empirical descriptions because it has been a focus of our research. We do not address potential explanations for sex similarities or differences, such as those derived from evolutionary (Archer, 2019; Geary, 2021) or sociocultural (Hyde, 2007, Hyde, 2014) theories, among others (see Eagly & Wood, 2013).

Section snippets

IQs and g

Substantial and reliable mean differences between the sexes have not materialized in either general intelligence (psychometric g)3 or intelligence in general (e.g., IQs). This finding is germane to the study of sex differences in

Broad and narrow/specific cognitive abilities

We reference Cattell-Horn-Carroll (CHC) theory (Carroll, 1993; Horn & Noll, 1997; Schneider & McGrew, 2018) to highlight and describe sex differences in specific abilities. CHC theory is widely used for intelligence research, test development, and assessment (Caemmerer, Keith, & Reynolds, 2020; McGrew, 2009). CHC theory is useful for classifying and organizing cognitive abilities (Reynolds, Keith, Flanagan, & Alfonso, 2013). Likewise, it is useful for organizing research findings. In this

Broad and specific academic achievement abilities

Sex differences in academic achievement scores are often included in descriptions of intelligence differences. The development of these achievement areas relies more on formal academic instruction, however. There are also many more large datasets available for achievement scores (e.g., National Assessment of Educational Progress). Here we discuss sex differences in writing, mathematics, and reading test scores, but do not summarize effect sizes. There are too many studies to summarize,

Important considerations for research in sex differences and specific abilities

Establishing empirical facts is essential to understanding sex differences–easier said than done. Study design and psychometric and participant sampling are critical, as selected measures and samples provide selected results. We address two matters in more detail. We are not the first researchers to address them, but they are worth reiterating and we offer some suggestions for future analyses.

Conclusion

The GSH shifted focus from differences to similarities between sexes. The shift, with the intent to promote more equality among the sexes, is noble. Regrettably, the GSH is at times interpreted to mean that no important sex differences exist in psychological variables. Likewise, similarities in general intelligence may be interpreted incorrectly to mean no important sex differences exist in human cognitive abilities. Here, using CHC theory as a guide to structure findings, we highlighted

References (88)

  • A.R. Jensen et al.

    Sex differences on the WISC-R

    Personality and Individual Differences

    (1983)
  • W. Johnson et al.

    Sex differences in mental abilities: g masks the dimensions on which they lie

    Intelligence

    (2007)
  • K.-J. Kan et al.

    On the interpretation of the CHC factor Gc

    Intelligence

    (2011)
  • T.Z. Keith et al.

    Sex differences in latent cognitive abilities ages 6 to 59: Evidence from the Woodcock–Johnson III tests of cognitive abilities

    Intelligence

    (2008)
  • T.Z. Keith et al.

    Sex differences in latent cognitive abilities ages 5 to 17: Evidence from the Differential Ability Scales—second edition

    Intelligence

    (2011)
  • P.A. Lowe et al.

    Gender differences in memory test performance among children and adolescents

    Archives of Clinical Neuropsychology

    (2003)
  • R. Lynn

    Sex differences in intelligence and brain size: A developmental theory

    Intelligence

    (1999)
  • R. Lynn et al.

    Sex differences on the WISC-R in New Zealand

    Personality and Individual Differences

    (2005)
  • R. Lynn et al.

    Sex differences in general knowledge

    Intelligence

    (2001)
  • K.S. McGrew

    CHC theory and the human cognitive abilities project: Standing on the shoulders of the giants of psychometric intelligence research

    Intelligence

    (2009)
  • S.D. Moffat et al.

    Navigation in a “virtual” maze: Sex differences and correlation with psychometric measures of spatial ability in humans

    Evolution and Human Behavior

    (1998)
  • M.H. Palejwala et al.

    Gender differences in latent cognitive abilities in children aged 2 to 7

    Intelligence

    (2015)
  • J.R. Pargulski et al.

    Sex differences in achievement: Distributions matter

    Personality and Individual Differences

    (2017)
  • P.D. Parker et al.

    Girls get smart, boys get smug: Historical changes in gender differences in math, literacy, and academic social comparison and achievement

    Learning and Instruction

    (2018)
  • L. Pezzuti et al.

    Are there sex differences in the Wechsler Intelligence Scale for Children—Fourth edition?

    Learning and Individual Differences

    (2016)
  • D. Reilly et al.

    Sex and sex-role differences in specific cognitive abilities

    Intelligence

    (2016)
  • M.R. Reynolds et al.

    A cross-battery, reference variable, confirmatory factor analytic investigation of the CHC taxonomy

    Journal of School Psychology

    (2013)
  • M.R. Reynolds et al.

    Sex differences in latent general and broad cognitive abilities for children and youth: Evidence from higher-order MG-MACS and MIMIC models

    Intelligence

    (2008)
  • M. Rosén

    Gender differences in structure, means and variances of hierarchically ordered ability dimensions

    Learning and Instruction

    (1995)
  • S. van der Sluis et al.

    Sex differences on the WISC-R in Belgium and the Netherlands

    Intelligence

    (2008)
  • S. van der Sluis et al.

    Sex differences on the Dutch WAIS-III

    Intelligence

    (2006)
  • R. Steinmayr et al.

    Gender differences on general knowledge tests: Are they due to differential item functioning?

    Intelligence

    (2015)
  • G. Stoet et al.

    Sex-specific academic ability and attitude patterns in students across developed nations

    Intelligence

    (2020)
  • J. Wai et al.

    Sex differences in the right tail of cognitive abilities: A 30-year examination

    Intelligence

    (2010)
  • J.A. Agelink van Rentergem et al.

    The factor structure of cognitive functioning in cognitively healthy participants: A meta-analysis and meta-analysis of individual participant data

    Neuropsychology Review

    (2020)
  • American Psychological Association

    Guidelines for psychological practice with lesbian, gay, and bisexual clients

    American Psychologist

    (2012)
  • J. Archer

    The reality and evolutionary significance of human psychological sex differences

    Biological Reviews

    (2019)
  • M. Asperholm et al.

    What did you do yesterday? A meta-analysis of sex differences in episodic memory

    Psychological Bulletin

    (2019)
  • A. Baye et al.

    Gender differences in variability and extreme scores in an international context

    Large-Scale Assessments in Education

    (2016)
  • J. Buckley et al.

    A heuristic framework of spatial ability: A review and synthesis of spatial factor literature to support its translation into STEM education

    Educational Psychology Review

    (2018)
  • J.B. Carroll

    Human Cognitive Abilities: A Survey of Factor-Analytic Studies

    (1993)
  • S.J. Ceci et al.

    Why Aren’t More Women in Science? Top Researchers Debate the Evidence

    (2007)
  • S.J. Ceci et al.

    Sex differences in math-intensive fields

    Current Directions in Psychological Science

    (2010)
  • M. Del Giudice et al.

    The distance between Mars and Venus: Measuring global sex differences in personality

    PLoS One

    (2012)
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