by Morton Hunt
To learn about the part played by nature and by nurture in scientific eminence, Galton invented another new research tool: the self-questionnaire. He drew up a set of questions about the respondent’s racial, religious, social, and political background, traits of character, and even hair color and hat size, and sent copies to two hundred members of the Royal Society. Among the crucial questions were: “How far do your scientific tastes appear to have been innate? Were they largely determined by events after you reached manhood, and by what events?”
Despite the questionnaire’s “alarming” length—Galton’s own rueful term—most of the subjects completed and returned it. (It was the first such questionnaire in history; today a researcher might get no such compliance.) When Galton tabulated the responses, he found that a majority believed their taste for science was innate; on the other hand, most respondents had a lot to say about how their education had either helped or hindered them. Galton felt obliged to admit that environmental factors, education in particular, could enhance or inhibit the development of scientific aptitude, and that its inheritance did not inevitably lead to success. Nonetheless, he maintained that hereditary aptitude had been shown to be the essential factor in scientific achievement.
Much later, as research methodology developed, it would become apparent that Galton’s questionnaire and his analysis of the data had serious weaknesses. For one thing, many of the questions, particularly those about the reasons for the respondents’ success, yielded purely subjective answers; for another, Galton had not given the questionnaire to noneminent scientists and nonscientists to see whether their answers were any different from those of eminent scientists; for a third, he had no way (though later he would invent one) to mathematically measure the relation between any two factors so as to judge whether it was accidental or significant. All the same, Galton’s use of the questionnaire and analysis of the data were innovations of immense value and have been important weapons in the armamentarium of psychological research ever since.
During the next decade Galton, now middle-aged, worked harder than ever at studies of individual psychological differences. In 1883 he published his observations on some thirty miscellaneous topics in an omnium gatherum titled Inquiries into Human Faculty and Its Development, a curious mixture of science and speculation, data and conjecture, statistics and anecdotes. Some of it purported to be science but was little more than Victorian male prejudice. In the chapter on “character,” for instance, Galton asserted without offering evidence that “one notable peculiarity in the character of the woman is that she is capricious and coy, and has less straightforwardness than the man.” He approved of this on evolutionary grounds: in courtship, were there no female hesitancy and male competition, “the race would degenerate through the absence of that sexual selection for which the protracted preliminaries of love-making give opportunity.”
But a good deal of Inquiries consisted of highly original scientific studies. One dealt with the ability to summon up mental images. Many nonscientists, Galton found, think in vivid images, many scientists in purely abstract terms, and he speculated that the ability to summon up sharp mental images hinders thinking in highly generalized and abstract terms. In another study he reported his invention of the word-association test; he drew up a list of seventy-five stimulus words and exposed them to his own view one by one, jotting down his first two or three associations to each. Most of what he learned was unremarkable, such as that, on repeating the test, he came up with the same associations. But there was genuine value to his observation that many of his associations sprang from his own experiences and that other people would be unlikely to have his associations. The result was that word-association tests became a leading way of studying individual personality traits.
Another noteworthy study was a report of one more Galton innovation. Still grappling with the problem of how to demonstrate the relative influences of nature and nurture on the development of the mind and personality, he had the brilliant idea of examining “the after-history of those twins who had been closely alike as children, and were afterwards parted, or who had been originally unlike and afterwards reared together.” He knew that twins came in two kinds: those who were physically almost identical and those who were no more alike than any other two siblings. If twins who were originally very similar became less so as they went through life, it could only be nurture that made them so; if twins who were originally dissimilar and were reared identically remained dissimilar, it could only be nature that kept them so.
It was a dazzling hypothesis, though Galton had only crude means of proving it. He sent a questionnaire to twins or relatives of twins he knew; he also asked them to give him the names of other twins. Eventually he had replies from ninety-four cases, eighty of which were of “close similarity” (probably identicals) and thirty-five of which provided enough details to be useful.
His report of the twin study is largely anecdotal; it tells of identicals who played tricks on people, or were both paddled by a schoolmaster who could not tell which one deserved punishment, of one who sometimes courted his brother’s fiancée, and so on. But when Galton sorted through his cases in search of identicals who became dissimilar in character, he found that, for some, “the resemblance of body and mind continued unaltered up to old age, notwithstanding very different conditions of life.” Others did exhibit differences, but in every case it was because an illness or accident had affected only one of the pair. In contrast, twins who had been dissimilar in childhood (probably fraternals), even if reared together and identically, did not become more alike over the years.12
Not one given to caution, Galton proclaimed, “There is no escape from the conclusion that nature prevails enormously over nurture when the differences of nurture do not exceed what is commonly to be found among persons of the same rank of society and in the same country.” From a contemporary perspective, the study was simplistic, imprecise, and far from conclusive. Still, it was a notable first, and the twin study method has been an important research strategy ever since and the most nearly definitive way of assessing the influences of heredity and environment on intelligence, personality traits, and other psychological characteristics.
Finally, Galton discussed in Inquiries his development of a number of mental tests in order quickly and simply to identify persons of superior intelligence, as part of his grand dream of improving the human race through eugenics. The year after Inquiries appeared, he began his trials of the tests at the International Health Exhibition, and when the fair closed down, he got permission from the South Kensington Museum to continue operating the laboratory there for a number of years. During that time he devised a number of new mental tests, among them a bar with a variable distance on it to test the ability to estimate extension, a rotating disk to test the ability to judge perpendicularity, sets of weights to be arranged in order of heaviness, and sets of bottles that contained aromatic material to be arranged according to intensity of odor.13
Galton was in his late sixties, far beyond the age at which scientists usually make their important discoveries, when he made his most important one. Appropriately, it involved his lifelong obsession, counting. Each kind of measurement made in the Anthropometric Laboratory had yielded a bell-shaped probability curve, but Galton sensed that he might glean other and highly significant information if he could discover how the different sets of measurements were related to one another. Some of the relationships were obvious—taller people, for instance, tended to weigh more—but what was the relationship between other sets of measurements? Which of them varied together and in the same degree? What did it mean if they did not vary in the same degree? Only by knowing how the data were related and which measures had little connection with the others would he be able to design an ideal battery of tests indicative of intelligence.
Galton had been led to consider this problem by an odd finding in his studies of hereditary genius: the children of unusual parents were generally less unusual. In terms of physical t
raits, for instance, the children of tall parents tended to be less tall, though still above average, and the children of short parents not as short, though still below average, a tendency Galton called “regression towards mediocrity” (later, the term became “regression towards the mean”). He wanted to know what it indicated about the strength of heredity and how he could express it mathematically. On the face of it, this seemed a purely intellectual puzzle; as it turned out, the solution to the problem would become one of the most useful research tools in psychology and many other sciences.
After pondering the matter for a long while, Galton set down a “scatter plot” of the heights of some three hundred children. First he created a grid, the horizontal dimension of which was children’s heights and the vertical dimension of which was parents’ heights (actually, the heights of “mid-parents”—the average of each parental pair). Then, in each cell of the grid (each intersection of a particular children’s height and a particular parental height) he wrote down the number of children who fit that category. The scatter plot looked like this:
For a time, it revealed nothing to him; then one morning, poring over it while waiting for a train, he suddenly saw a regularity in the numbers. If he drew a line connecting any set of approximately equal values, it would describe a tipped-over ellipse whose center point was the midpoint of the scatter plot (the averages for both parents and children). When he did so and then drew lines across the ellipse connecting its extreme horizontal and vertical points, they passed through the average height of children in each vertical column and the average height of parents in each horizontal row. It looked like this:
The ellipse and the lines crossing it revealed the relationship he had been looking for. At any given parental height (“Locus of horizontal tangential points”), the average height of the children was only about two-thirds as far from the mean (average) as that of the parents; that is, the children had “regressed” a third of the way toward the mean.14 Conversely, for any children’s height (“Locus of vertical tangential points”), parents were somewhat closer to the mean (that is, parents of unusual children were less unusual than their children).
Galton had discovered the analytical device of the “regression line.” If the children’s heights had been exactly the same as the parents’, the two regression lines would have coincided; if the children’s heights had no relation whatever to the parents’, the regression lines would have been perpendicular to each other. As it was, they were fairly close, meaning that the relation between the two variables in this case—their correlation— was about midway between total and nil.
That was in 1886. Ten years later the British biometrician Karl Pearson, a Galton disciple and later his biographer, worked out a mathematical means of calculating the “coefficient of correlation”—which he called r, for regression—without any need to create scatter plots. For any two sets of data, it would show a correlation ranging from 1 (a perfect one-to-one covariation) to 0 (no relationship whatever) and to −1 (a totally inverse relationship). The Pearsonian method has been the standard way of evaluating correlation to this day. In the case of parents and children, r turned out to be .47 (somewhat different from Galton’s first calculations): that is, children averaged about half as far from the population’s average as their parents.15
The importance of Galton’s discovery of correlation analysis can hardly be overestimated. It meant that whenever two variables change in the same direction (or the opposite direction), even though not to the same degree, they are correlated, and the strength of the correlation indicates how meaningful the relationship between them is. The stronger the relationship, the less likely it is happenstance and the more likely the connection is causal. One variable may be the cause (or a contributing cause) of the other, or vice versa, or they may be the concurrent and linked effects of some other cause. In either case, a strong correlation suggests an explanation of the phenomenon under study. In the numbers are, if not answers, at least clues.
(Even a strong correlation, to be sure, may be “spurious”—an artificial result of some other cause. In men, for instance, the degree of baldness correlates with length of marriage—not because one has any connection with the other but because age is related to each. Later techniques of analysis have been able to screen out such misleading correlations.)
The psychologist George Miller, appraising the value of Galton’s discovery, writes:
Covariation is a central concept, not only for genetics and psychology, but for all scientific inquiry. A scientist searches for the causes of events; all he ever finds are correlations between antecedent and consequent conditions… Galton’s insight has been, and continues to be, essential for vast stretches of modern social and behavioral science, and is useful in countless ways to engineers and natural scientists as well.16
Add to that his many other important methodological contributions and one can see why, although Galton was not a profound thinker, Raymond Fancher says that “few men have had greater impact on modern psychology.”17
Galtonian Paradoxes
The outcome of Galton’s work is a paradox. Although several of his methodological inventions are of vital importance in contemporary psychological research, his name means little to most psychologists and is all but unknown to the public. Working alone outside a university setting, he created no school of psychology, supervised no doctoral dissertations, and had few followers. Moreover, his chief contributions were research methods rather than illuminating theories, but the world remembers the latter, even though ingenious research methods are often the route to great insights.
And there is another and larger paradox. The measuring of individual differences in intelligence, a prominent goal of Galton’s life, has had a great impact on Western society since the early part of the present century—but not by means of his method. Although he conceived of and originated mental testing, his name is not linked with any of the tests used today or in the past ninety years; except in histories of psychology, he is remembered, if at all, as the originator not of mental testing but of eugenics.
In Great Britain, Galton was the founder of a “new psychology” of individual differences, but almost no British psychologists thought of themselves as Galtonians.18 In the latter part of the nineteenth century most British experimental psychologists went to Germany for training and brought Wundtian procedures and theory back with them. They adopted many of Galton’s ideas and methodological inventions but considered themselves Wundtians. The new German psychology was held in much greater esteem than the British; it was the product of the university system and was “pure,” while Galton’s was the product of a gifted amateur and was intended to serve practical purposes.
Galton’s effect was greatest in America, but again not in the form of a school of psychology. Before the turn of the century, many American psychologists were structuralists (Wundtians), who had no interest in the measurement of individual differences. By 1905 the functionalists (Jamesians) were dominant, but though they were sympathetic to many of Galton’s ideas, they defined themselves in grander theoretical terms than those of his psychology. Like William James, many leading figures in American psychology, including John Dewey, James Rowland Angell, George H. Mead, James McKeen Cattell, Edward Lee Thorndike, and Robert S. Woodworth, based their theories on the evolutionary selection of the mentally fittest and its social equivalent, the struggle to get ahead. None called himself a Galtonian, but they shared a utilitarian outlook and all of them, therefore, valued Galton’s methods of measuring individual differences because the methods were so practical.19
The most enthusiastic advocate of anthropometric measurement was James McKeen Cattell (1860–1944).20 Born in Easton, Pennsylvania, and educated there at Lafayette College, he went to Leipzig in 1883 and studied with Wundt until 1886. His main research interest was the study of reaction times, but he was a fiercely independent young man and dared to differ with the great Wundt on a key methodological issue: Cat-tell doubted that anyo
ne could really introspect in the manner called for by Wundt, namely, by subdividing reaction time into perception, choice, and so on. As a consequence, Cattell, though he was Wundt’s laboratory assistant, had to carry out some of his work in his own quarters, because Wundt would not allow in the laboratory research by those who could not or would not follow his introspection method.
Cattell was intrigued by the differences in reaction time among the people he tested, and discussed it as a matter of “special interest” in an 1885 paper.21 After earning his doctorate the following year, he went to London, met Galton, and, despite nearly a forty-year gap in their ages, found him a kindred spirit. Deeply impressed by Galton—many years later Cattell called him “the greatest man whom I have known”—he worked for him off and on for two years in the Anthropometric Laboratory at the South Kensington Museum and became thoroughly conversant with the tests performed there.
In 1888, at only twenty-eight, Cattell became a professor of psychology at the University of Pennsylvania (probably the first person in the world to hold that title; James, at Harvard, was not designated a professor of psychology until the following year). Cattell assembled a set of fifty tests, some Galtonian and some adapted from Fechner, Wundt, and other sources, and administered ten of them to his students to measure individual differences in intelligence. He supposed, as Galton had, that the chiefly physical characteristics measured by the tests were related to intelligence: strength of grip, speed of arm movement, reaction time to sound, just noticeable differences in weight, memory span for letters, and five others. In 1890, he described his work in a paper, in the journal Mind, called, “Mental Tests and Measurements”; it was the first use of that term and launched the mental-testing movement.
