INTELLIGENCE TESTS. An intelligence test or intelli gence examination is an instrument to measure the amount of intelligence shown by a human being or a lower animal. The instrument consists of a series of questions to be answered, or directions to be followed, or things to be learned, or intellectual tasks of any sort to be performed. Intelligence or intellect may be defined as the ability to perform intellectual tasks; and an intelli gence test is a specially instructive sampling of such tasks.
Sample Tests.—The tasks shown below are representative of those used in standard intelligence tests.
"Show me your nose. Put your finger on your nose." Same with eyes, mouth and hair. Three responses out of four must be correct. What is the difference between: (a) Laziness and idleness; (b) Evolution and revolution ; (c) Poverty and misery ; (d) Character and reputation.
Repeating three digits. After some explanation and practice, the person tested is asked to say 6-4-1, then to say 3-5-2, then to say 8-3-7. The test is passed if one series out of three is repeated without error, after a single hearing.
Repeating six digits reversed. The series used are
and 7-5-2-6-3-8. The test is passed if one series out of three is repeated without error.
Tom runs faster than Jim. Jack runs slower than Jim. Which is the slowest of the three? After some explanation and practice, the person tested is asked to "Finish what I say." At night you sleep in . . . Mary has a ring on her . . . You wear gloves on your . . . You wear a . . . on your head.
person who has been tested in respect of an examination consisting of from so to 20o such tasks may be given a score, and so be put in comparison with all others who have been tested with the same collection of tasks.
to certain limitations, the score may be expressed in terms of a mental age, that is, the age at which the average child is able to attain it. Thus if John Doe, aged 12•0, scores 118 in the National Intelligence Examination, and if the average child of age 13.1 attains a score of 118 in this examination, John Doe has a mental age of 13.1 years. John Doe's intelligence quotient, or I.Q. is his mental ageXloo divided by his chronological age, that is 13 I X Ioo or 109.
I2.0 This form of statement is useful for individuals whose scores are not higher than those made by the average child of 14, and whose chronological ages are not over 18. For higher levels and later ages the method is of doubtful value.
The score may also be expressed in terms of the percentage of some defined group who would attain lower scores than it. Thus, if 71% of persons aged 12-0 score lower than 118, and 29% score higher, in the National Intelligence Examination, John Doe may be recorded as in the 71 percentile for his age. This method is especially useful in the case of the higher levels of intelligence and adult ages. A more refined measure of this type expresses any individual's score as a plus or minus deviation from the average for some defined group in terms of the variability of that group as a unit.
There are 3o or more such intelligence exam inations now in use. Some, like the Pintner-Cunningham Pri mary Tests, are adapted to measure very young children aged two to five years. The National Intelligence Examination is designed to fit the intellects of the level of ordinary children from 9 to 15. The Terman Group Test is especially suited to measure young people from 14 to 20. Some, like the Thorndike Examination for High-School Graduates, are adapted to measure gifted adults. Some, like the Army Group Examination Alpha, require an ability to read and write; some, like the Binet, are given orally ; some, like the Army Beta, are largely independent of language. Some, like the Otis Group Intelligence Scale, meas ure chiefly intellect as it operates with words and numbers and abstract relations ; some are more concerned with information about things and persons. In some, the speed of response counts a great deal in determining the score made; in others, it counts very little, the time allowed being sufficient to permit almost everybody to do almost everything of which he is capable.
Existing instruments for measur ing intelligence developed from three roots : the tests of sensory acuity, memory, attention and the like devised in the early history of psychology ; the interview, as of physician with patient or employer with candidate for employment ; and the school examination. Galton, Cattell and Binet were pioneers in this field of psychology. Sir F. Galton's Inquiries into Human Fac ulty (1883) presented the general problem of the measurement of individual differences ; and he soon thereafter set up in the South Kensington Museum in London a laboratory where any person could be measured in a series of physical and mental traits. Under the influence especially of Cattell, many short examinations or "tests" of special mental powers were devised and rather widely used in the United States from 1890 on. Im portant work was done by Kraepelin and Ebbinghaus in Ger many. An eminent French psychologist, Alfred Binet, using the general form of an interview between physician and patient, enriched by suggestions from psychological tests proper, pro duced in 1905 what may be called a standardized interview, con sisting of 3o questions and tasks, many of which were chosen from the tests of special powers now familiar to all psycholo gists. This "metric scale of intelligence" was further improved and divided into age levels in 1908, and finally revised in 1911. Many variations of it have been used in different countries.
While Binet was developing a scientific interview and record and score, various psychologists in America were testing children in groups by means of printed collections of tests. The next step was the arrangement of such a collection in a standardized unitary examination, after the general plan of written examina tions in school subjects. One of the earliest and by far the most influential of such arrangements was the group examination Alpha prepared in 1917 for measuring recruits in the U.S. Army. This examination was taken by nearly 2,000,000 men, large groups (sometimes over i,000) being sometimes examined at one time and place.
Since then, intelligence examinations have increased rapidly in number, have become diversified in nature, and have been much improved in respect of convenience in giving and scoring. They are widely used, especially in the United States, as an aid in the proper grading and classifying and treat ment of school children ; and in studies of special groups such as defectives, delinquents and dependents. The methods used in conducting intelligence examinations are also being applied to examinations in school subjects, producing the so-called "new type" examinations and educational achievement tests. At least 1,000,000 such examinations were made in the case of school children alone in the year 1925. Some of the leading American universities require an intelligence examination as a part of the general admission requirement.
In spite of notable improvements during the last 20 years, existing instruments for measuring intelligence suffer from serious deficiencies. An intelligence examination is still a more or less undefined collection of tasks, its score is still a somewhat arbi trary summation of credits, and the correspondence of the scores to the abilities which they purport to measure is still far from perfect. Psychologists are working to supply these defi ciences, seeking to replace the undefined collections of tasks by tasks rigorously defined in nature and graded by a true scale of intellectual difficulty, so that the score may mean the precise height of intellectual difficulty which the person in question can master (see EXAMINATIONS).
Binet and T. Simon, "Methodes nouvelles pour Bibliographyr-A. Binet and T. Simon, "Methodes nouvelles pour le diagnostic du niveau intellectuel des anormaux," Annee Psy chologique, vol. II, pp. 191-244 (1905) ; G. M. Whipple, Manual of Mental and Physical Tests (1910) ; L. M. Terman, The Measure ment of Intelligence (1919) ; W. Stern, Die Intelligenz der Kinder and Jugendlichen (1920) ; R. M. Yerkes and others, "Psychological Exam ining in the United States Army," Memoirs of the National Academy of Sciences, vol. 15 (1921) ; C. Burt, Mental and Scholastic Tests (1921) ; R. Pintner, Intelligence Testing (1923) ; C. Spearman, The Nature of "Intelligence" and the Principles of Cognition (1923) ; K. Young, "The History of Mental Testing," Pedagogical Seminary, vol.
pp. 1-48 (1924) ; E. L. Thorndike, and others, The Measurement of Intelligence (1926) ; see ABILITIES, and INTELLIGENCE, HUMAN.
(E. L. T.)
