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Clark Wissler (1870-1947) is best known today as an influential American anthropologist, but his early training was in psychology. His 1901 doctoral dissertation created an academic uproar by purportedly debunking some of the most influential intelligence theories of the time. The controversy was made scandalous by the fact that Wissler’s findings discredited the research of his mentor, James McKeen Cattell. (Fancher, 1985, p. 48-49)
Impact of Wissler’s Dissertation
Later Career of Wissler
Francis Galton (1822-1911) was a believer in the hereditary basis of intelligence, and is credited with popularizing the phrase “nature and nurture.” He originated and named the eugenics movement, in service of which he created the basic idea of the intelligence test. (It is important to note however, that the term “intelligence test” did not come into being until later.) (Fancher, 1985)
Galton believed that intelligence was a matter of neurological efficiency. Therefore, he theorized that it could be tested by measuring reaction time and sensory acuity. In the mid 1880s he established an anthropometric laboratory at London’s South Kensington Museum, cleverly enticing visitors to spend three pence apiece to enjoy the novelty of undergoing a variety of psychophysical tests. Besides providing amusement for the museum’s patrons, this unusual laboratory provided a vast amount of research data. (Fancher, 1985, pp. 36-37; Sternberg, 1990, p. 70-71)
At about the same time, an American doctoral student, James McKeen Cattell (1860-1944) was conducting a series of reaction time experiments in Germany. When he became aware of Galton’s anthropometric laboratory, he began to correspond with him, and designed a series of 50 psychophysical tests based on Galton’s earlier work. He established his own anthropometric laboratory at Cambridge University, and became a successful international advocate of the psychophysical approach to mental testing. (Fancher, 1985, pp. 45-47)
The work of these two men was of pivotal importance to the field of experimental psychology. Psychophysical testing had great popular appeal, and was being enthusiastically embraced by researchers from many different countries. (Fancher, 1985, pp. 47-48)
The surprising result was that there was virtually no correlation between scores on Cattell’s tests and academic achievement. Perhaps equally surprising was the fact that scores on Cattell’s tests did not even appear to correlate with each other. Since the tests didn’t agree among themselves, and they didn’t correlate with independent measures of mental ability (undergraduate academic grades), it did not seem possible that they could be valid measures of intelligence. (Fancher, 1985, pp. 48-49; Sternberg, 1990, pp. 72-73)
Many critics have pointed out that Wissler’s research was flawed. When Charles Spearman first heard of the dissertation, he was disheartened. However, he soon realized that there was a degree of unreliability in Cattell’s sensory discrimination scores. Therefore, Wissler’s correlation coefficients would have underestimated the degree of the relationships between variables. Spearman believed that applying a correction formula to the original data would allow the true degree of relationships to be assessed. (Fancher, 1985, pp. 88-89)
Other critics have argued that even if Wissler’s correlations were correct, the inferences based on his results were not. Wissler’s research subjects were members of a very homogeneous group, i.e., undergraduate students from prestigious universities. Since these students were relatively similar to one another, correlations would be expected to be lower than those obtained from a more heterogeneous group. (Sternberg, 1990, pp. 73-74)
Later Career of Wissler
Although Clark Wissler left the field of psychology behind a century ago, psychology has not left him behind. His doctoral dissertation permanently changed the dominant research paradigm for intelligence testing. (Fancher, 1985, p. 49) Although advances in neurophysiology may eventually impact intelligence testing, anthropometric testing (as it was conceived by Galton, Cattell, Wissler and others) is rarely used today.
Freed, S.A., & Freed, R.S. (1992). Clark Wissler. In P.H. Raven (Ed.), National Academy of Sciences of the United States of America Biographical Memoirs, 61, 468-497. Washington D.C.: National Academy Press.
Sternberg, R.J. (1990). Metaphors of mind: Conceptions of the nature of intelligence. Cambridge: Cambridge University Press.