The study of individual differences, which today occupies one of the most important fields of psychology, has its roots in Francis Galton’s theory of intelligence .
This researcher, besides being a pioneer in several branches of science (among them, meteorology), designed some of the first tools to measure intellectual capacities, which allowed him to reach interesting conclusions about human intelligence and its relationship with inherited characteristics.
Who was Francis Galton?
Galton was born in England in 1822 into a wealthy family, which allowed him to be surrounded by a very active intellectual environment. He was a cousin of Charles Darwin, who decades later would lay the foundations of biology by refuting creationism and Lamarck’s theory of the evolution of species.
Darwin was a great influence on Francis Galton , and partly because of this he was interested in answering one of the great questions of psychology: are we who we are because of what we have learned or because of what we have inherited in an innate way through our parents? Galton’s theory of intelligence was intended to provide an answer to part of this question: the question of our mental abilities to solve problems.
The Foundations of Galton’s Theory of Intelligence
At the time Francis Galton lived, it was only beginning to be understood that life forms contain a series of genes that shape them, since Gregor Mendel, the researcher who initiated the studies in genetics, was also born in 1822. However, it was already intuited that, in some way, the characteristics of the fathers and mothers, or at least a part of them, pass to their offspring, forming the basic features of their biology.
On the other hand , it was understood that education and the influence of the environment have an impact on who we are and how we behave, and that this impact already has an effect on our first weeks of life, being confused with the first forms of expression of our genes.
Francis Galton was counting on the fact that both heredity and learning are mixed in shaping not only our physical characteristics but also our psychological ones, but he wanted to know which of the two elements explained a greater part of the variance in the general human population. He used tools that began to be widely used in the 19th century, partly because of him: statistics and tools for measuring psychological characteristics.
Studying the intellect
Galton designed ‘a series of questionnaires to measure the traits and characteristics of population groups he considered relevant, seeing that people in a better social and economic position tended to give greater signs of intelligence than the rest . These studies also allowed him to see that intelligence, like physical characteristics, is expressed statistically through a normal distribution: the great majority of people had a level of intelligence very close to the average, while people with extreme values (due to their very low or very high intelligence) are always clear minorities.
Seeing that statistics could be very useful for knowing the mental characteristics of our species and the way in which individual differences are expressed in it, he decided to use it to check the validity of his hypotheses about intelligence. He had come to the conclusion that the most intelligent people were a minority and that this coincided with the more affluent minority, but… was this a sign that expensive education favoured the development of great intellects, or is it that the biological inheritance of rich families tends to generate intelligent individuals?
Nature vs. Learning: Twin Studies
To answer the previous question, Francis Galton decided to look for cases in which the influence of innate inheritance could be ruled out , which would allow us to see the effects of learning. That is, he resorted to the study of monozygotic twins. Studying the differences in mental characteristics of these twins over several years, he observed something curious: they could be very different or very similar, but this pattern rarely changed over time. That is, twins who were very similar at birth continued to look alike much later, and twins who were very different from their early years continued to look alike in later stages.
This discovery led Francis Galton, while acknowledging the influence of learning and the environment on the individual, to give more importance to the innate and the inheritance received by the parents: in the end , the effects of a constantly changing environment did not seem to be very significant in the psychological traits of the twins , which remained more or less the same over time.
Galton and Eugenics
This idea was also expressed in Francis Galton’s theory of intelligence, which understood the intellect as one more tool created by evolution and the selection of the best adapted individuals. As the most intelligent people had a greater capacity to adapt to new situations, this was a great evolutionary advantage that needed to be enhanced. Unfortunately, since Francis Galton adopted an innate position , this meant that for this researcher eugenics, or the selection of individuals with better innate traits , was a politically and socially useful measure.
Unlike the “racial cleansing” plans embraced by the Nazis decades later, however, Galton advocated positive eugenics: giving advantages to the population with the best biological heritage, rather than putting up barriers to the rest of the population. In practice, however, positive eugenics remained a clearly discriminatory proposal, providing support for the supremacist movements already in the making.
- Pueyo, Andrés. (2013). Psychology of individual differences (in Catalan). Barcelona: Librería universitaria de Barcelona.
- Sternberg, R. J.; Salter, W. (1982). Handbook of human intelligence. Cambridge, UK: Cambridge University Press. ISBN 0-521-29687-0OCLC11226466.
- Triglia, Adrian; Regader, Bertrand; Garcia-Allen, Jonathan. (2018). What is intelligence? From the IQ to multiple intelligences. EMSE Publishing.