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The following page consists of an essay on the gender differences in intelligence 

“Men are (on the whole) more intelligent than women” (Irwing & Lynn, 2005). Critically examine this statement in the context of the available empirical evidence.


For many years, psychologists have attempted to find out who is the smarter sex. The purpose of this report is critically to evaluate Irwing and Lynn’s (2005) statement above using empirical evidence. This is a difficult task because there is no agreed consensus as to what intelligence actually means (Eysenck, 1986; El Asam, 2012a). Generally, psychologists performing psychometric tests calculate and assess differences among subjects with varying intellectual ability, while cognitive psychologists focus their attention on how individuals reason and solve problems (Van Herwegen, 2012).


In the first half of the 20th century, intelligence tests focussed on the Stanford-Binet Intelligence Test (Binet, 1905; Binet & Simon, 1911), ‘g factor’ (Jensen, 1998; Spearman, 1904; Thurstone, 1936), and IQ tests (Stern, 1912) and there are several examples that show that there was no significant difference between the sexes (Terman, 1916; Spearman, 1927). Catell (1963) and Horn & Cattell (1966), who defined ‘fluid and crystallised’ intelligence, also showed no significant difference between the sexes. During the second half of the twentieth century, where, in some cases, these intelligence tests were replaced by Wechsler’s Adult Intelligence Scale (WAIS) (Wechsler, 1955) and Raven’s Progressive Matrices (Raven, 1939), most researchers concluded that there were no significant differences between males and females (Court, 1983; Macintosh, 1996, 1998). It was not until 1990s, that Lynn (see Lynn, 1994, 1998, 1999) suggested that, overall, after the age of 15, boys had a mean score of intelligence which was between 2-5 points higher than girls. He suggested that females develop later than boys and that, from the age of 15 onwards, the male advantage was about 5 IQ points (Lynn & Irwing, 2004). This study was a meta-analysis from 57 studies in the general population using Standard and Advanced Progressive Matrices which tested non-verbal, abstract reasoning. Arguably, this is the best way to test for Spearman’s ‘g’ (Court, 1983; Jensen, 1998) and fluid intelligence (Mackintosh, 1998).


However, the author feels that this generalization has a number of problems; indeed, some important questions should be asked in order to challenge Irwing and Lynn’s (2005) statement—questions proposed by Al Asam (2012b). For instance, should IQ tests be used by teachers to stream individuals at school? Should employers base their decisions on employment solely on these tests? To answer this latter question, it is important to consider how employers choose potential staff. In many cases, the ‘sifting process’ begins with IQ tests, the evaluation of CVs and covering letters; however, as ‘possibles’ become more ‘probables’, forward-thinking employers might turn to using more evaluative means of choosing the right person., while using expressions such as, ‘He felt right for the company’, or, ‘She seems to fit in well in the team’. In these instances, the employer is evaluating perhaps more important abilities and qualities in a potential employee, such as emotional intelligence (Harris, 1995), creative skills, practical sense, developed intelligence, prior experience, wisdom and social sensitivity.


It is perhaps more helpful for us to think of intelligence as a more interactive phenomenon, and this coincides with more recent findings cognitive neuroscience: for example, researchers who have focussed on hemispheric asymmetry (Hellige, 1993) have proposed that comprehension and fluency are located in numerous parts of the brain (Halpern, 1997). In fact, if we work on the assumption that all intellectual skills can be improved with practice and learning (Lövdén & Lindenberger, 2005; Maguire, Woollett & Spiers, 2006)—which one can call ‘developed learning’—then all individuals who take an IQ examination, a test which supposedly measures innate intelligence, start either with a headstart or a handicap. As we know from studies (for example, Erickson, Colcombe, Wadhwa, Bherer, Peterson, Scalf, & Kramer, 2007), IQ can also be developed over a period of time, and the plasticity of the brain is such that, assuming there is no damage to the brain due to Alzheimer’s or excessive drinking, one can continue to learn and develop in old age.


Psychologists have looked at the importance of social learning for many years (Grusec, 1992), and this is important to consider when discussing sex differences in intelligence. Our interaction with our parents and peer-groups can have a profound effect on our intelligence. Greenough, Black and Wallace (1987) demonstrated that being placed in an academically-stimulating surrounding had an effect on the brain in that it created new synaptic connections and charges. Certainly, since the beginning of the 20th century, society has moved on by accepting women into many professions, but one is forced to consider the rôle of expectation in the nurture of women’s intelligence in the past, and also amongst some populations today Eccles, 1987). For example, in the first half of the 20th century, girls were often not expected to go onto university or to develop a career, and this low expectation at home was compounded by peer pressure and gender stereotyping (Halpern and LaMay, 2000; Rimm, 2002; Rose & Rudolph, 2006). Indeed, this is still the case in some countries (Abbas, 2002); furthermore, in many cases throughout the world, women are in charge of looking after children (Burns & Homel, 1998; Wetherell, Stiven & Potter, 2011). This may cause a differential experience between men and women with regard to prior learning, expectation as well as affecting cognitive ability.


There are many questions that are left unanswered with regard to the definition of intelligence and this is why it is impossible to ascertain the smarter sex; in addition, the structures of intelligence—for example, Horn and Cattell’s (1966) fluid intelligence and crystalized intelligence and ‘second order factors’ which include general visualization and fluency—cannot be considered as universal truths across cultures (Van Herwegen, 2012). For example, Americans tend to rate intelligence on natural ability whereas the Japanese stress the importance of hard work (Holloway, Kashiwagi, Hess & Azuma, 1986). A more ‘inclusive’ set of criteria for intelligence is Howard Gardner’s ‘multiple intelligences’ (Gardner, 1993). The premise of this theory is that, rather than having one single intelligence score (g), intelligence is a combination of spatial, linguistic, interpersonal, intrapersonal, logical-mathematical, bodily-kinaesthetic, musical, ‘naturalistic’ and ‘existential’ abilities. If intelligence is contingent process in which individuals are able to demonstrate their ability to judge, reason and think rationally, then surely all ‘normally functioning’ individuals have the ability to build on their skills in all nine areas. Gardner’s theory, although criticized by Scarr (1985) and Anderson (1992) for not identifying the differences between behaviour and cognition, is still relevant to gender differences in intelligence. For example, even though Gardner did not use the term ‘emotional intelligence’ (EI) (Salovey and Mayer, 1990), his theories on intrapersonal intelligence and interpersonal intelligence are inextricably interconnected to EI. In addition, later versions of the theory have been adapted to include more of the cognitive components of intelligence (Mayer and Salovey, 1997), and there is also evidence to support the view that EI can be reliably measured (Ciarrochi, Chan, Caputi & Roberts, 2001; Mayer, Salovey, Caruso & Sitarenios, 2003). EI is also important for our every-day behaviour, social learning and the development of intelligence. For example, Brackett, Mayer & Warner (2004) measured the EI of students in the USA (n=330): women scored significantly higher than men on EI. The authors pointed out that low EI scores were connected with negative behaviours—e.g. drug use and alcohol abuse—in males but not for females. These negative behaviours could have a deleterious effect on the development of intelligence. Overall results from Goleman’s studies on emotional intelligence (Goleman, 2001) revealed that there was a small effect size to show that women obtained slightly higher results on emotional intelligence, whereas results from Emmerling and Goleman’s (2003) mixed ability models of EI concluded that there were no differences between the sexes.


Quite apart from emotional intelligence, there are several specific cognitive tests and performance tasks in which women have obtained higher mean scores: these include reading comprehension (Hedges & Nowell, 1995), fine motor tasks (for example mirror tracing) (O’Boyle & Hoff, 1987); higher grades at school (Stricker, Rock & Burton, 1993), verbal fluency (Hines, 1990), associative memory (Birenbaum, Kelly & Levi-Keren, 1994), amongst many others. And, although males tend to score more highly on tasks that use spatial ability, ‘scholastic skills’ (Jensen, 1969) and fluid reasoning (Hedges & Nowell, 1995), females, overall, are more developed with regard to speech, comprehension, semantic processing and fine motor skills.


In conclusion, there are several unknowns with regard to the nature of intelligence. For instance, what is the nature of the genetic influence? Why does the impact of genetic influence increase with age? What is the effect of nutrition on intelligence and neurotransmitter activity? What is the effect of hormone levels on cognitive ability across the menstrual cycle where oestrogen levels change (Hampson, 1990) and how do varying testosterone levels in men affect performance (Choi & Silverman, 2002)? And, why have these influences not been taken into consideration in analyses of intelligence? Differences in intelligence depend on the type of cognitive test and the prior education of each participant (Halpern, 1997). There is no one standardized intelligence test. Perhaps, more insightful results can be seen from specific IQ differences—such as mechanical reasoning (male advantage), spelling (female advantage), mental rotation (male advantage) and speech production (female advantage) —all of which have been shown to have had significant differences for either men or women (Linn & Petersen, 1985; Feingold, 1994; Hide & Linn 1988). Finally, results from many of these studies (for example Irving & Lynn, 2004) are based on means scores, and nobody is average (Halpern, 1997); moreover, the spread, and this can be seen in the standard deviations, are more pronounced in the male scores. This makes the 5 IQ point male advantage less relevant. Although this report has not made any claims to the question of who is the smarter sex, it has attempted to provide the reader with a more appropriate way of understanding and evaluating intelligence.

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Abbas, T. (2002). A retrospective study of South Asian further education college students and their experiences of secondary school. Cambridge Journal of Education, 32(1), 73-90.

Binet, A (1904). A propos de la mesure de l’intelligence. L’Année psychologique, 11(1), 69-82.

Binet, A., & Simon, T. (1911). Development of intelligence in the child 1 [Russian translation]. Moscow.

Birenbaum, M., Kelly, A. E., & Levi-Keren, M. (1994). Stimulus features and sex differences in mental rotation test performance. Intelligence, 19(1), 51-64.

Brackett, M. A., Mayer, J. D., & Warner, R. M. (2004). Emotional intelligence and its relation to everyday behaviour. Personality and Individual differences, 36(6), 1387-1402.

Burns, A., & Homel, R. (1989). Gender division of tasks by parents and their children. Psychology of women quarterly, 13(1), 113-125.

Cattell, R. B. (1963). Theory of fluid and crystallized intelligence: a critical experiment. Journal of Educational Psychology, 54(1), 1-22.

Choi, J. & Silverman, I. (2002). The relationship between testosterone and route-learning strategies in humans. Brain and Cognition, 50, 116-120.

Ciarrochi, J., Chan, A. Y. C., Caputi, P., & Roberts, R. (2001). Measuring emotional intelligence. In C. Ciarrochi, J. P. Forgas, & J. D. Mayer (Eds.), Emotional Intelligence in Everyday Life: a Scientific Inquiry (pp. 25–45). Philadelphia, PA: Psychology Press.

Court, J. H. (1983). Sex differences in performance on Raven’s Progressive Matrices: A review. Alberta Journal of Educational Research, 29, 54–74.

Eccles, J. S. (1987). Gender roles and women’s achievement-related decisions. Psychology of Women Quarterly, 11(2), 135-172.

El Asam A (2012a, October 25, 2012). ‘Gender and Intelligence’. Conference presentation at Kingston University, London.

El Asam A (2012b, October 25, 2012). Seminar on ‘Gender and Intelligence’, Kingston University, London.

Emmerling, R. J., & Goleman, D. (2003). Emotional intelligence: Issues and common misunderstandings. Issues in Emotional Intelligence, 1(1), 1-32.

Erickson, K. I., Colcombe, S. J., Wadhwa, R., Bherer, L., Peterson, M. S., Scalf, P. E., … & Kramer, A. F. (2007). Training-induced plasticity in older adults: effects of training on hemispheric asymmetry. Neurobiology of Aging, 28(2), 272-283.

Eysenck, H. J. (1986). A theory of intelligence and the psychophysiology of cognition. In R. J. Sternberg (Ed.), Advances in the psychology of human intelligence (Vol. 3, pp. 1–34). Hillsdale, NJ: Erlbaum.

Feingold, A. (1994). Gender differences in personality: A meta-analysis. Psychological Bulletin, 116, 429–456.

Gardner, H. E. (1993). Multiple intelligences: the theory in practice. New York: Basic Books.

Goleman, D. (2001). An EI-based theory of performance. In C. Cherniss & D. Goleman (Eds), The Emotionally Intelligent Workplace (pp. 27-44). New York: Jossey-Bass.

Greenough, W. T., Black, J. E., & Wallace, C. S. (1987). Experience and brain development. Child development, 58: 539-559.

Grusec, J. E. (1992). Social learning theory and developmental psychology: The legacies of Robert Sears and Albert Bandura. Developmental Psychology, 28(5), 776.

Halpern, D. F. (1997). Sex differences in intelligence: Implications for education. American Psychologist, 52(10), 1091-1102.

Halpern, D. F., & LaMay, M. L. (2000). The smarter sex: A critical review of sex differences in intelligence. Educational Psychology Review, 12(2), 229-246.

Hampson, E. (1990). Estrogen-related variations in human spatial and articulatory-motor skills. Psychoneuroendocrinology, 15(2), 97-111.

Harris, J. R. (1995). Where is the child’s environment? A group socialization theory of development. Psychological review, 102(3), 458-489.

Hedges, L. V., & Nowell, A. (1995). Sex differences in mental test scores, variability, and numbers of high-scoring individuals. Science, 269, 41-45.

Hellige, J. B. (1993). Hemispheric asymmetry: What’s right and what’s left. Cambridge, MA: Harvard University Press.

Hines, M. (1990). Gonadal hormones and human cognitive development. Brain and behavior in vertebrates, 1, 51-63.

Holloway, S. D., Kashiwagi, K., Hess, R. D., & Azuma, H. (1986). Causal attributions by Japanese and American mothers and children about performance in mathematics. International Journal of Psychology, 21(1-4), 269-286.

Horn, J. L., & Cattell, R. B. (1966). Refinement and test of the theory of fluid and crystallized general intelligences. Journal of Educational Psychology, 57(5), 253-270.

Irwing, P & Lynn, R (2005). Sex differences in means and variability on the progressive matrices in university students: a meta-analysis. British Journal of Psychology, 96(4), 505-524.

Jensen, A. R. (1969). How much can we boost IQ and scholastic achievement. Harvard Educational Review, 39(1), 1-123.

Jensen, A. R. (1998). The G Factor. Westport, CT: Praeger.

Linn, M. C., & Peterson, A. C. (1985). Emergence and characterisation of sex differences in spatial ability: A meta-analysis. Child Development, 56, 1479–1498.

Lövdén, M., & Lindenberger, U. (2005). Development of intellectual abilities in old age: From age gradients to individuals. Handbook of understanding and measuring intelligence, 203-221.

Lynn, R. (1994). Sex differences in brain size and intelligence: A paradox resolved. Personality and Individual Differences, 17, 257–271.

Lynn, R. (1998). Sex differences in intelligence: A rejoinder to Mackintosh. Journal of Biosocial Science, 30, 529–532.

Lynn, R. (1999). Sex differences in intelligence and brain size: A developmental theory. Intelligence, 27, 1–12.

Lynn, R & Irwing P (2004). Sex differences on the progressive matrices: a meta analysis. Intelligence, 32, 481-498.

Mackintosh, N. J. (1996). Sex differences and IQ. Journal of Biosocial Science, 28, 559–572.

Mackintosh, N. J. (1998). Reply to Lynn. Journal of Biosocial Science, 30, 533–539.

Maguire, E. A., Woollett, K., & Spiers, H. J. (2006). London taxi drivers and bus drivers: a structural MRI and neuropsychological analysis. Hippocampus, 16(12), 1091-1101.

Mayer, J. D., & Salovey, P. (1997). What is emotional intelligence? In P. Salovey, & D. Sluyter (Eds.), Emotional Development and Emotional Intelligence: Educational Implications. New York: Basic Books.

Mayer, J. D., Salovey, P., Caruso, D. R., & Sitarenios, G. (2003). Measuring emotional intelligence with the MSCEIT 2.0. Emotion, 3(1), 97-105.

O’Boyle, M. W., & Hoff, E. J. (1987). Gender and handedness differences in mirror-tracing random forms. Neuropsychologia, 25(6), 977-982.

Raven, J. C. (1938). Progressive Matrices: Sets A, B, C, D, and E. University Press: HK Lewis.

Rimm, S. (2002). Peer pressures and social acceptance of gifted students. The social and emotional development of gifted children, 2, 13-18.

Rose, A. J., & Rudolph, K. D. (2006). A review of sex differences in peer relationship processes: potential trade-offs for the emotional and behavioral development of girls and boys. Psychological bulletin, 132(1), 98.

Salovey, P., & Mayer, J. D. (1990). Emotional intelligence. Imagination, cognition and personality, 9(3), 185-211.

Scarr, S. (1985). An author’s frame of mind: review of frames of mind by Howard Gardner. New Ideas in Psychology, 3, 95-100.

Spearman, C. (1904). ” General Intelligence,” objectively determined and measured. The American Journal of Psychology, 15, 201-292.

Spearman, C. (1927). The measurement of intelligence. Nature, 120, 577-578.

Stern, W. (1912). The psychological methods of intelligence testing. G. Whipple, (Trans). Baltimore: Warwick and York.

Stricker, L. J., Rock, D. A., & Burton, N. W. (1993). Sex differences in predictions of college grades from scholastic aptitude test scores. Journal of Educational Psychology, 85(4), 710-718.

Terman, L. M. (1916). The measurement of intelligence: An explanation of and a complete guide for the use of the Stanford revision and extension of the Binet-Simon intelligence scale. Boston: Houghton Mifflin.

Thurstone, L. L. (1936). A new conception of intelligence. Educational Record.

Van Herwegen J (October 11, 2012) ‘Intelligence 1’. Conference presentation at Kingston University, London.

Wechsler, D. (1955). Manual for the Wechsler Adult Intelligence Scale. Oxford: Psychological Corporation.

Wetherell, M., Stiven, H., & Potter, J. (2011). Unequal egalitarianism: A preliminary study of discourses concerning gender and employment opportunities. British Journal of Social Psychology, 26(1), 59-71.


This essay was written by psychotherapist and critical psychologist, David Kraft (PhD).


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