In addition to the Terman American examiners are wont to use the Binet tests prepared by Dr. Goddard. t: recently of the Vineland Training School, h Dr. Kuhlmann, of Faribault, Minn., by is late Dr. Huey, formerly of Johns Hopkins 1:o. versity, or by Dr. Wallin of the Saint Losi5 public schools. Whatever be the precise forn employed, the Binet tests yield results, know as the "mental age.* If this coincides with is chronological age the child is said to b' "normal" or °at age ; if the mental age ):e higher the child is "mentally advanced,' 'acre crated,' 'superior' or °gifted' ; if the men age be lower the child is °mentally retardet.' °inferior," "dull" or "subnorniaL* It is CV: tomary to indicate the degree of relatively, by multiplying the mental age by lil and dividing by the chronological, or 1::t age: then, as will be understood, the 'intelligeso quotient," or "I. Q.," is 100 or thereabouts : the average or so-called "normal' child. rc. below 100 for those below average mentally r' above 100 for those above average menial./ Roughly speaking, a child with an I. Q. below 80 may be termed mentally subnormal and alien 120 may be termed gifted. About five childrs in 100 are as inferior and about five are :-, superior as indicated by I. Q.'s of 80 and IZ respectively.
The amount of activity stimulated lw 6 work of Binet has been truly surprising. Sr' liographies prepared by Dr. Kohs list 711 boo: and articles dealing with the Binet tests Z. to 1917. Practical application has been as common in the direction of Binet's original i.e., in detecting subnormal mentality and); measuring its degree. Thus, special classes :* backward or for subnormal or for adult feeble-minded children are now common:* recruited with the aid of these tests. in juvenile courts the tests have proved valosS: in showing the presence of arrested men development or low degrees of general genre in a large proportion of the delinque brought to trial.
Among other developments from the origri Binet scale should be mentioned the Yerke Bridges "Point Scale in which many of 'It Binet tests are used, but a method of scoriae by points is substituted for the Binet age-lot principle.
The usefulness of the Binet method. gra' as it undeniably is, is purchased at the expeng of certain limitations: finer differences or type of intelligence are not well ed• adults cannot be so successfully tested children; it cannot be administered ously to a group of persons.
The sporadic efforts of various psychologists to overcome these limitations, to develop a series of group tests to measure the general mental ability of adults, have been powerfully stimu lated and co-ordinated by the advent of the war. As a result of preliminary trials in 1917 there has been developed and put into wholesale operation in the army cantonments a system of mental testing that virtually affords a 'mental survey" of the distribution of intelligence in all the various groups of men composing a modern army. The system includes, beside the regular group tests, special tests for men who do not speak or write English well, and also various supplementary individual tests for the exami nation of men who fail to do well in the regular group tests.
It is clear already that the successful use of mental tests in the army, following the success obtained in educational and correctional institu tions, will contribute much to the spread of the idea that a measurement of mental ability is as important and as feasible (even if not always as precise) as a measurement of physical ability. The idea that applicants for positions in com mercial and industrial organizations — salesmen. clerks, skilled workers, executives— should demonstrate their mental ability by passing suitable mental tests is bound to make rapid headway ; similarly, the idea that in our public schools the most efficient instruction demands the segregation of children into groups of approximately like native ability as well as of approximately like school attainments.
These rapid developments in the use of mental tests will mean the creation of a new profession—that of the consulting or the applied psychologist. We may expect that in the not distant future persons of varying de grees of expertness will proffer their services in applying mental tests to the solution of vari ous educational, sociological, medical, industrial and commercial problems. It will become neces sary for the sake of this new profession of "human engineering' to warn the public against the charlatans who are already trading on the name of °psychologist') In essence, the situa tion would appear to be this: the mere quasi mechanical administering of well-known tests, like the Binet tests, may be entrusted to a person of comparatively meagre professional training; the interpretation of the results of tests demands a fair working knowledge of psychology, a good college training and perhaps a year of special drill in the handling of tests under direction; the devising of tests to meet special needs, the prescription of educational, sociological, peno logical and other treatment for the modification of human behavior demands not merely these qualifications but also a well-rounded and in tensive knowledge of mental life and a system atic knowledge of psychology, in other words, demands the psychologist as well as the °mental tester.)) We may expect that eventually some sort of public if not legal recognition will be given to these different uses of mental tests and to the qualifications necessary for under taking them.
Alfred, 'Development of Intelligence in Children) (trans. by E. S. Kite, 1906, Training School, Vineland, N. J., Research Department, Publication 11) : and 'Mentally Defective Children) (trans. by Drum mond, with appendix containing Binet-Simon tests 1914); Pinter, R. and Patterson, D. G., 2d ed., Baltimore 1914 and 1915) ; Yerkes, R. M., Bridges, J. W., and Hardwick, Rose, 'A Point Scale for Measuring Mental Ability) (Baltimore 1915).