Francis Galton William Revelle Northwestern University Francis Galton (1822-1911) was among the most influential psychologists of the 19th century. He did pioneering work on the correlation coefficient, behavior genetics and the measurement of individual differences. He introspectively examined the question of free will and introduced the lexical hypothesis to the study of personality and character. In addition to psychology, he did pioneering work in meteorology and introduced the scientific use of fingerprints. Whenever he could, he counted. Sir Francis Galton (Feb 16, 1822 - Jan 17, 1911) the time he was eight, had accomplished what a nor- was among the preeminent psychologists of the 19th mal 16 year old could do. Thus Terman estimated century. Born to a wealthy English family he was Galton’s IQ as surpassing 200. able to devote his life to a variety of scientific in- Although trained in mathematics and medicine quiries. Although best known to psychologists for at Cambridge, when he was 22 the death of his fa- his pioneering work on the correlation coefficient ther and the resulting inheritance allowed him to and the study of individual differences in intellec- forgo continuing in medicine and instead to sat- tual ability, he also did fundamental research on be- isfy the desire to travel he had acquired as a bril- havior genetics, meteorology, and the use of finger- liant if somewhat cavalier student. In 1845 Gal- prints for identification. ton travelled through Egypt (which at the time in- Galton was born on February 16, 1822 near cluded Sudan) and went slightly beyond Khartoum Sparkbrook (now part of the inner city of Birming- and briefly explored the upper regions of the White ham, England) to a successful Quaker family who and the Blue Nile, before continuing on to Syria, manufactured guns during the early 1800s. Through Lebanon and exploring the Jordan River towards the his maternal grandfather, Erasmus Darwin, he was Dead Sea. Such travels, which by end of the 19th a half cousin of Charles Darwin. Galton was the century would seem a natural part of a young per- youngest of seven children and his early childhood son’s “Grand Tour”, at the time were considered ex- memories reflected the love of his family as they in- otic and temporarily satisfied his wanderlust. Gal- culcated him with a love of literature, science, and ton spent the next few years enjoying the idle life of mathematics. Based on Karl Pearson’s four volume a country squire, hunting and fishing while simulta- biography of Galton, Terman (1917) analyzed Gal- neously reading and thinking about science. ton’s intellectual accomplishments as a child and es- In 1850 he proposed to the Royal Geographical timated Galton’s mental age as a child as roughly Society to undertake (and finance) an exploration twice his physical age. That is, at age five he was of South West Africa. For the next two years his reasoning as would a normal ten year old, and by journeys in what is now Namibia led him through previously unexplored (by Europeans) regions. His writings describing the perils of lions, elephants and his dealings with marauding and feuding tribesmen were extraordinarily detailed and yet remain to this contact: William Revelle [email protected] day enjoyable to read. He measured longitude by Version of March 1, 2014 the lunar distance method used by sailors without To appear in Cautin, R. and Lilienfeld, S (Eds) The Ency- access to accurate chronometers; latitude by the tra- clopedia of Clinical Psychology. Wiley-Blackwell ditional use of a sextant to measure the elevation of This is the submitted LATEXversion and might differ from stars; and elevations of mountains by the tempera- the final published version. ture of boiling water. Upon his return to England he 2 WILLAM REVELLE wrote up a descriptive narrative of his travels (The study genetics. narrative of an explorer in Tropical South Africa, Having read the work of Quetelet on the distribu- 1853) as well as a thoughtful survival guide for the tion of many natural phenomenon, Galton was most traveller (The art of travel, 1855). The acclaim he taken with the idea of what has come to be called received for his travels and his writings led to his the normal curve and variation around the central election to the RGS and led him to devote his con- tendency. He designed and had built a mechanical siderable energies in scientific pursuits rather than apparatus, a quincunx, to demonstrate how the nor- his previous life of hunting with his country friends. mal normal curve is the result of many independent By 1862 his interests had turned to meteorology; random events. Based upon these observations was by organizing data collection all over western Eu- his letter to Nature in 1874 proposing a basic met- rope he was able to distinguish between cyclonic ric (his “common statistical scale” which was con- (where the winds blow counter clockwise) and anti- ceptually equivalent to the modern z score) which cyclonic weather patterns. The style of maps he expressed deviations from the median in terms of developed to show these patterns of low and high the probable error (or half the interquartile range). pressure zones are used to this day. His interest in To Galton, the advantages of the median and the in- meteorology led him to be a member of the mete- terquartile range were that they were easier to find orological council for 34 years where he continued by casual observation than were the mean and stan- to advance the science of meteorology. dard deviation. Galton’s interest in meteorology illustrates his Subsequent work with the genetics of height in fascination with numbers. His personal maxim was humans and size in the garden pea led him to in- to “Count where ever you can” and he did so by ob- troduce the concept of reversion to mediocrity (re- serving everything from the number of fidgets ob- gression to the mean) and to the concept of the re- served during a lecture to personal ratings of the gression slope relating parent to offspring. With a beauty of women throughout the United Kingdom. flash of insight based upon the different slopes of He developed simple instruments to help him record parent to child and child to parent, he derived the his observations, such as pricking a pin into a note co-relation index (1888). Subsequent work by Pear- card in different locations as he listened to a lecture son, Wentworth, and Yule led to the formalization of and observed people fidgeting. this concept as what we now know as the Pearson Inspired by reading On The Origin of Species Product Moment Correlation Coefficient. by his cousin, Charles Darwin, Galton published a His later research on individual differences number of articles examining how scientific, liter- (1891) led to his introduction of using fingerprints ary, and legal talent tended to run in families. He as a means of identification. Galton realized that considered the obvious explanation of social class for fingerprints to be useful there needs to be evi- and social opportunity but marshalled evidence such dence for constancy across the life span, that there is as that even among the elite students who attended suitable variation in fingerprints to define someone Cambridge the top scorers on English or Mathe- uniquely, and finally, that one could develop a lexi- matics examinations were much more frequently con of fingerprints, such that an expert could iden- related than expected by chance. His analysis re- tify them. He was able to demonstrate that all three sulted in several volumes studying the sources of conditions held. eminence, the first of which Hereditary Genius: His interests in measuring individual differences An Inquiry into Its Laws and Consequences (1869) led him to arrange (at his own expense) to collect elaborates his evidence that talent runs in families data at the International Exposition of 1894 in Lon- and that the effect is weaker the more remote the don. He arranged to measure “Keenness of Sight relationship. Galton proudly reports in his biogra- and of Hearing; Color Sense, Judgment of Eye; phy (Memories of my life, 1908) the letter he re- Breathing Power; Reaction Time; Strength of Pull ceived from Darwin expressing great enthusiasm for and of Squeeze; Force of Blow, Span of Arms; the book. A subsequent volume on the topic of the Height, both standing and sitting; and Weight”. The sources of scientific eminence led to him to consider success of his measurements at the International Ex- the sources of talent due to nature or nuture (his position led him to continue collect similar data at a terms) as well as the power of the twin design to museum for the next six years. GALTON 3 In considering which individual differences are If he had merely contributed the correlation coeffi- important for understanding and describing char- cient, his impact would have been substantial. But acter, Galton reviewed his basic genetic approach, he went far beyond that by starting the fields of be- the use of the twin method in quantitative genetics, havior genetics, introducing the nature/nurture dis- and reported on his own introspection on the little tinction, formalizing the study of ability, introduc- amount of his behavior that exemplified free will ing the lexical hypothesis, and much more. He jus- rather than on the normal consequences of habit and tifiably is known as one of the great polymaths of situation (Measurement of Character, 1884). He the 19th century. continued his discussion of determining the rele- vant aspects of character by consulting Roget’s The- See Also saurus and found at least 1,000 words that differed slightly in meaning when describing character.