Arthur Jensen



Arthur Jensen is a Professor Emeritus of educational psychology at University of California, Berkeley. Jensen is known for his work in psychometrics and differential psychology, which is concerned with how and why individuals differ behaviorally from one another. He is a major proponent of the hereditarian position in the nature versus nurture debate, the position that concludes genetics play a significant role in behavioral traits, such as intelligence and personality traits. He is the author of over 400 scientific papers published in refereed journals.

Jensen was born August 24, 1923, to a Polish Jewish mother and a Danish father. Jensen studied at University of California, Berkeley (B.A. 1945), San Diego State College (M.A., 1952) and Columbia University (Ph.D., 1956). In the late 1950s, Jensen did his postdoctoral research in London. Upon returning to the United States, Jensen became a researcher and professor at the University of California, Berkley, where he focused on individual differences in learning, especially the influences of culture, development, and genetics on intelligence and learning. He has concentrated much of his work on the learning difficulties of culturally disadvantaged students.

IQ and academic achievement
Jensen's interest in learning differences directed him to the extensive testing of black, Mexican-American, and other minority-group school children. The results led him to distinguish between two separate types of learning ability. Level I, or associative learning, may be defined as retention of input and rote memorization of simple facts and skills. Level II, or conceptual learning, is roughly equivalent to the ability to manipulate and transform inputs, that is, the ability to solve problems. Statistical analysis of his findings led Jensen to conclude that Level I abilities were distributed equally among members of all races, but that Level II occurred with significantly greater frequency among whites and Asian-Americans than among African-Americans and Mexican-Americans.

Jensen's most controversial work, published in February 1969 in the Harvard Educational Review, was titled "How Much Can We Boost I.Q. and Scholastic Achievement?" It concluded, among other things, that "head start" programs designed to boost African-American IQ scores had failed, and that this was likely never to be remedied, largely because, in Jensen's estimation, over 70% of the within race IQ variability was due to genetic factors, and the 30% left over was due to non-shared environmental influences (e.g., prenatal drug exposure, placental nutrient competition  when there are multiple births).

When the work was initially published, students and faculty staged large, loud protests outside his University of California, Berkeley office, and he received multiple death threats. He was even denied reprints of his work by his publisher and was not permitted to reply in response to letters of criticism -- both extremely unusual and exceptional policies for their day. Many colleagues at the time felt that even if Jensen's work contained no scientific merit, his treatment was itself against the spirit of science and the free exchange of ideas.

In a later article, Jensen argued that his claims had been misunderstood:


 * ...nowhere have I "claimed" an "innate deficiency" of intelligence in blacks. My position on this question is clearly spelled out in my most recent book: "The plain fact is that at present there exists no scientifically satisfactory explanation for the differences between the IQ distributions in the black and white populations. The only genuine consensus among well-informed scientists on this topic is that the cause of the difference remains an open question" (Jensen, 1981a, p. 213).

Thomas Sowell wrote:
 * Professor Jensen pointed out back in 1969 that black children's IQ scores rose by 8 to 10 points after he met with them informally in a play room and then tested them again after they were more relaxed around him. He did this because "I felt these children were really brighter than their IQ would indicate." What a shame that others seem to have less confidence in black children than Professor Jensen has had.

Nevertheless, eugenicists and others point to passages such as the following (from his book The g Factor: The Science of Mental Ability) to support their claim that Jensen has proven that differences in IQ scores between races are mostly genetic:
 * In Chapter 12: Population Differences in g: Causal Hypotheses, Jensen writes: "The relationship of the g factor to a number of biological variables and its relationship to the size of the white-black differences on various cognitive tests (i.e., Spearman's hypothesis) suggests that the average white-black difference in g has a biological component. Human races are viewed not as discrete, or Platonic, categories, but rather as breeding populations that, as a result of natural selection, have come to differ statistically in the relative frequencies of many polymorphic genes. The genetic distances between various populations form a continuous variable that can be measured in terms of differences in gene frequencies. Racial populations differ in many genetic characteristics, some of which, such as brain size, have behavioral and psychometric correlates, particularly g."

Gould's criticism
Paleontologist Stephen Jay Gould, known for his popularizations of science in mass market books and magazines, attacked Jensen's work in his 1981 book The Mismeasure of Man.

Gould makes three criticisms. The first is the criticism commonly leveled against Jensen and other researchers dealing with race and intelligence:that Jensen misapplies the concept of "heritability." Heritability measures the percentage of variation of a trait due to inheritance, within a population. (Gould 1981: 127; 156-156). Jensen has used the concept of heritability to measure differences in inheritance between populations, and this is the basis of the criticism.

Secondly, Gould disagrees with Jensen's belief that IQ tests measure a real variable, g, or "the general factor common to a large number of cognitive abilities" which can be measured along a unilinear scale. This is a claim most closely identified with Cyril Burt and Charles Spearman. According to Gould, Jensen misunderstood the research of L. L. Thurstone to ultimately support this claim; Gould however argues that Thurstone's factor analysis of intelligence revealed g to be an illusion (1981: 159; 13-314).

Third, Gould disagrees with Jensen's support of the attempts of others to calculate the IQ's of dead people (such as the famous astronomer and Prussian monetary theorist Nicolaus Copernicus) (1981: 153-154).

In a 1982 review of Gould's book Jensen gives point-by-point rebuttals to Gould's characterizations of his work, including Gould's treatment of heritability, the "reification" of g and the use of Thurstone's analysis. Gould's responses can be found in the latest edition of The Mismeasure of Man (1996).

Jensen's response and criticism
In Arthur Jensen's response to Gould's criticisms, in the paper titled The Debunking of Scientific Fossils and Straw Persons., Jensen begins his paper with this observation


 * "Stephen Jay Gould is a paleontologist at Harvard's Museum of Comparative Zoology and offers a course at Harvard entitled, "Biology as a Social Weapon." Apparently the course covers much the same content as does the present book. Having had some personal cause for interest in ideologically motivated attacks on biologically oriented behavioral scientists, I first took notice of Gould when he played a prominent role in a group called Science for the People and in that group's attack on the theories of Harvard zoologist Edward O. Wilson, a leader in the development of sociobiology..."

Jensen adds that Gould made a number of misrepresentations, whether intentional or unintentional, while purporting to present Jensen's own positions


 * "In his references to my own work, Gould includes at least nine citations that involve more than just an expression of Gould's opinion; in these citations Gould purportedly paraphrases my views. Yet in eight of the nine cases, Gould's representation of these views is false, misleading, or grossly caricatured. Nonspecialists could have no way of knowing any of this without reading the cited sources. While an author can occasionally make an inadvertent mistake in paraphrasing another, it appears Gould's paraphrases are consistently slanted to serve his own message."

See also: the discussion of intelligence testing and race and intelligence.

The g Factor
The g Factor: The Science of Mental Ability (1998) is considered by supporters to be Jensen's magnum opus on the general intelligence factor (g). The book deals with the intellectual history of the discovery of g and various models of how to conceptualize intelligence, and with the biological correlates of g, its heritability, and its practical predictive power.

Clocking the Mind
Clocking the Mind : Mental Chronometry and Individual Differences (to be published in April 2006) is on mental chronometry (MC), a variety of techniques for measuring the speed with which the brain processes information. Whereas IQ merely represents an ordinal (ranking) scale and thus possesses no true scale properties, Jensen argues mental chronometry represents a true natural science of mental ability.

Interviews
SASP Interviews: Arthur R. Jensen. Beaujean, A. A. (2002, July). SASP News, 2 (4). (pdf)

"A Conversation With Arthur Jensen (Part 1)". (1992). American Renaissance, 3(8).

"A Conversation With Arthur Jensen (Part 2". (1992). American Renaissance, 3(9).

Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen. (2002) Miele F, Jensen AR. Westview Press. ISBN 081334008X

Selected Articles & Book Chapters
Rushton, J. P., & Jensen, A. R.. (2005). Thirty years of research on Black-White differences in cognitive ability. Psychology, Public Policy, & the Law, 11, 235-294. (pdf)

Rushton, J. P., & Jensen, A. R. (2005). Wanted: More race-realism, less moralistic fallacy. Psychology, Public Policy, and Law, 11, 328-336. (pdf)

Rushton, J. P., & Jensen, A. R. (2003). African-White IQ differences from Zimbabwe on the Wechsler Intelligence Scale for Children-Revised are mainly on the g factor. Personality and Individual Differences, 34, 177-183. (pdf)

Jensen, A. R. (2002). Galton's legacy to research on intelligence. Journal of Biosocial Science, 34, 145-172.

Jensen, A. R. (2002). Psychometric g: Definition and substantiation. In R. J. Sternberg, & E. L. Grigorenko (Eds.). The general factor of intelligence: How general is it? (pp. 39-53). Mahwah, NJ, US: Lawrence Erlbaum.

Jensen, A. R. (2000). Testing: The dilemma of group differences. Psychology, Public Policy, & Law, 6, 121-128.

Jensen, A. R. (1998) The g factor and the design of education. In R. J. Sternberg & W. M. Williams (Eds.), Intelligence, instruction, and assessment: Theory into practice. (pp. 111-131). Mahwah, NJ: Lawrence Erlbaum.

Jensen, A. R. (1996). Giftedness and genius: Crucial differences. In C. P. Benbow, & D. J. Lubinski (Eds), Intellectual talent: Psychometric and social issues (pp. 393-411). Baltimore: Johns Hopkins University.

Jensen, A. R. (1995). Psychological research on race differences. American Psychologist, 50, 41-42.

Jensen, A. R. (1993). Spearman's g: Links between psychometrics and biology. In F. M. Crinella, & J. Yu (Eds.), Brain mechanisms: Papers in memory of Robert Thompson (pp. 103-129). New York: Annals of the New York Academy of Sciences.

Jensen, A. R. (1993). Why is reaction time correlated with psychometric g? Current Directions in Psychological Science, 2, 53-56.

Jensen, A. R. (1989). The relationship between learning and intelligence. Learning and Individual Differences, 1, 37-62.

Kranzler, J. H., & Jensen, A. R.(1989). Inspection time and intelligence: A meta-analysis. Intelligence, 13, 329-347.

Jensen, A. R. (1974). Ethnicity and scholastic achievement. Psychological Reports, 34, 659-668.

Jensen, A. R. (1974). Kinship correlations reported by Sir Cyril Burt. Behavior Genetics, 4, 1-28.