Richard Lynn

Gender differences in extraversion, neuroticism, and psychoticism in 37 nations

Mean gender differences on Eysencks three personality traits of extraversion, neuroticism, and psychoticism were collated for 37 nations. Women obtained higher means than men on neuroticism in all countries, and men obtained higher means than women on psychoticism in 34 countries and on extraversion in 30 countries. The relation between the magnitude of the gender differences and per capita incomes was not significant for any of the three traits.

Sex differences in intelligence and brain size: A paradox resolved

Abstract Males have larger brains than females, even when corrected for body size, and brain size is positively correlated with intelligence. This leads to the expectation that males should have higher average levels of intelligence than females. Yet the consensus view is that there is no sex difference in general intelligence. An examination of the literature shows that the consensus view is wrong. Among adults, males have slightly higher verbal and reasoning abilities than females and a more pronounced superiority on spatial abilities. If the three abilities are combined to form general intelligence, the mean for males is 4 IQ points higher than the mean for females. Among children up to the age of around 14 yr the sex differences are smaller because girls mature earlier than boys. The evolutionary selection pressures responsible for greater intelligence in males are discussed.

Streaming in the Primary School.

Professor Lynn suggests that two investigations carried out by Dr. Barker Lunn have yielded inconsistent results: the first (cross‐sectional) study showed that the attainment of children in streamed schools was superior and the second (longitudinal) study showed that streamed children did better on one set of tests and unstreamed children did better on a parallel set of tests. He suggests that the children in the first study were crudely matched for social class, and that both studies fail to solve the problem of streaming because of possible statistical distortions in the analysis. Dr. Lunn replies that the apparently inconsistent results were due to the differences in the aims of the two stages. The cross‐sectional stage, examining absolute measures of attainment, was exploratory‐‐factors such as the individual pupils social class, and his initial ability were not taken into account. The second or main longitudinal stage was concerned with the progress of one age group of children comparable in terms o...

Sex Differences in Intelligence and Brain Size: A Developmental Theory.

In 1992, it was reported by Ankney and Rushton that males have larger average brain size than females even when allowance is made for body size. It is known that brain size is associated with intelligence, and it would therefore be expected that males would have higher intelligence than females. Yet it has been universally maintained that there is no difference in intelligence between the sexes. It is proposed that this anomaly can be resolved by a developmental theory of sex differences in intelligence which states that girls mature more rapidly in brain size and neurological development than boys up to the age of 15 years. The faster maturation of girls up to this age compensates for their smaller brain size with the result that sex differences in intelligence are very small, except for some of the spatial abilities. From the age of 16 years onwards, the growth rate of girls decelerates relative to that of boys. The effect of this is that a discernible male advantage of about 4 IQ points develops from the age of 16 into adulthood, consistent with the larger average male brain size. This paper presents new evidence on the developmental theory of sex differences in intelligence and discusses alternative attempts to deal with the anomaly by Ankney (1995), Mackintosh (1996), and Jensen (1998).

The role of nutrition in secular increases in intelligence

Abstract In a number of economically developed nations the intelligence of the population has increased by approx. 1 standard deviation (SD) over the last half century. No satisfactory explanation for this increase has yet been forthcoming. In this paper it is argued that the major causal factor is improvements in nutrition. These have led to parallel increases in height, head circumference and brain size, and to improved neurological development and functioning of the brain. These are responsible for higher intelligence. Nutrition is still suboptimal for substantial proportions of the population and further increases in intelligence can be anticipated if standards of nutrition could be improved.

Sex differences in means and variability on the progressive matrices in university students : A meta-analysis

A meta-analysis is presented of 22 studies of sex differences in university students of means and variances on the Progressive Matrices. The results disconfirm the frequent assertion that there is no sex difference in the mean but that males have greater variability. To the contrary, the results showed that males obtained a higher mean than females by between .22d and .33d, the equivalent of 3.3 and 5.0 IQ conventional points, respectively. In the 8 studies of the SPM for which standard deviations were available, females showed significantly greater variability (F(882,656) = 1.20, p < .02), whilst in the 10 studies of the APM there was no significant difference in variability (F(3344,5660) = 1.00, p > .05).

National differences for thirty-seven nations in extraversion, neuroticism, psychoticism and economic, demographic and other correlates

Summary-National mean scores for extraversion, neuroticism and psychoticism were obtained for a large sample of nations together with national means for the work ethic and competitiveness. These data were intercorrelated with additional variables including per capita incomes and national prevalence rates of suicide, homicide and alcoholism. The results showed a number of significant relationships. Factor analysis revealed the presence of three factors which were interpreted as extraversion, neuroticism and psychoticism. The contribution of questionnaire data and demographic indices as methods for measuring national differences in personality is discussed

The intelligence of the Mongoloids: A psychometric, evolutionary and neurological theory

Abstract This paper presents a theory of the intelligence of the Mongoloids consisting of three linked sub-theories. The first concerns the psychometric features of Mongoloid intelligence and proposes that Mongoloids are characterised by high general intelligence (Spearmans g), high visuospatial abilities and low verbal abilities. Mongoloid abilities also display slow maturation in infancy and early childhood. It is proposed that this pattern of abilities cannot be explained in environmental terms and should be regarded as substantially genetically programmed. The second sub-theory presents an evolutionary explanation for this pattern of abilities in Mongoloids, whereby it is proposed that the extreme cold of the ice ages acted as a selection pressure for increases in Spearmans g and the visuospatial abilities. The low verbal abilities and slow maturation rates are interpreted as by-products of these adaptations. The third sub-theory presents a neurological model for the Mongoloid brain in which it is proposed that cortex devoted to the visuospatial abilities was expanded at the expense of the cortex devoted to the verbal abilities. The implication that there exists a negative correlation between the visuospatial abilities and the verbal abilities is considered in the concluding part of the paper and shown to be correct.

The rise of national intelligence: Evidence from Britain, Japan and the U.S.A.

Abstract It is estimated that national mean intelligence has been rising in Britain by 1.71 IQ points per decade since 1932. In Japan the mean national IQ has been increasing by 7.70 IQ points per decade since 1950, but the rate of gain in Japan has been decelerating. These figures can be compared with a rate of gain of 3.0 IQ points per decade in the U.S.A. since 1932. In both Britain and the U.S.A. the IQ gains have been greater for non-verbal than for verbal intelligence but there is conflicting evidence on this point for Japan. In Britain IQ gains have been greatest at the lower end of the intelligence distribution, indicating a contraction in the range of intelligence among the contemporary population.

Testing the developmental theory of sex differences in intelligence on 12–18 year olds

Abstract The consensus view states that there are no sex differences in intelligence. However, Lynn (1994, 1999) has formulated a developmental theory of sex differences in intelligence that challenges that view. The theory states that boys and girls mature at different rates such that the growth of girls accelerates at the age of about 9 years and remains in advance of boys until 14–15 years. At 15–16 years the growth of girls decelerates relative to boys. As boys continue to grow from this age their height and their mean IQs increase relative to those of girls. This paper presents new evidence for the theory from the Spanish standardization sample of the fifth edition of the DAT. 1027 boys and 924 girls between 12 and 18 years were tested. The general trend shows that girls do better at the younger ages and their performance declines relative to boys among older age groups, which supports the developmental theory. The sex difference for the DAT as a whole for 18 year olds is a 4.3 IQ advantage for boys, very close to the advantage that can be predicted from their larger brain size (4.4 IQ points). The profile of sex differences in abilities among the Spanish sample is closely similar to that in the United States and Britain, which is testimony to the robustness of the difference in these different cultures.