Psychological testing and assessment has its origins in an interest in individual differences, which led to the development of specific tests for educational placement and psychological characteristics.
Sir Francis Galton(1822-1911) maintained a lifelong interest in individual differences in abilities. His convictions about the origins of individual differences were apparently influenced by ideas about physiognomy.
Galton sought to identify key physical differences between "eminent" British citizens and their undistinguished, anonymous countrymen. He believed that the "eminence" of successful statesmen and scholars could be traced to such physical distinctions as head size, distance between the eyes, length of nose and hand-grip strength.
Galton failed to take into account important differences in education and environment(nurture) as well as inherited physical traits(nature), and failed to confirm his hypothesis. Nonetheless his early efforts mark the beginning of psychology's continued interest in assessing individual differences.
In 1905 the French educator Alfred Binet(1857-1911) was asked by the French government to devise a means of classifying students for entry into a new nation-wide public education system. Binet and his colleague Theophile Simon(1837-1961) developed a test of age-graded items -- questions to answer, problems to solve -- for students to respond to, rather than measuring their head size or visual acuity. This was the forerunner of what we now call the intelligence test.
In 1916 Lewis Terman(1877-1956), on the faculty of Stanford University, revised the original Binet-Simon test, dubbing the new version the Stnaford-Binet. The Stanford-Binet test score was expressed as an Intelligence Quotient (I.Q). The I.Q is calculated by dividing the respondent's mental age by his or her chronological age, then multiplying by 100(to get an integer): IQ = MA/CA X 100.
Both the Binet-Simon and the Stanford-Binet tests were designed to be administered to one respondent at a time. After the outbreak of World War I, however, there emerged a need for a system for testing large numbers of military inductees to make appropriate leadership and task assignments. One psychologist, James McKeen Cattell(1860-1944), involved himself in this effort despite his personal opposition to America's entry into the war. Cattell had been Wilhelm Wundt's first laboratory assistant at Leipzig. In his career he pursued psychometric studies(measurement of psychological characteristics) as well as founding and editing several influential journals, including Psychological Review. The standardized tests so familiar to American college students are a modern legacy of the work of Cattell and other early assessment developers.
One of the most well-know psychological assessment techniques is the inkblot test. Swiss psychiatrist Hermann Rosrschach(1884-1922) first employed subjects' interpretations of inkblot shapes as keys to dimensions of personality. In 1935 American psychologist Henry A. Murray(1893-1988) and his colleagues developed the Thematic Apperception Test (TAT), a technique in which a subject examines and tells stories about each of a series of pictures. Both the Rorschach and the TAT are termed projective techniques because the subject is assumed to project his or her own needs and character onto an ambiguous test stimulus -- one which can be interpreted in different ways -- in developing a story or description.
The best known objective technique for assessing personality is the Minnesota Multiphasic Personality Inventory (MMPI), develped by two University of Minnesota faculty members in 1943. The MMPI consists of 550 true-false items, whose response pattern reveals the respondent's scores on various personality traits first dianosed among a large clinical population, a group of patients in a setting like a clinic or psychiatric hospital.
The Sixteen Personality Factor Inventory(16PF), a personality inventory standardized on a normal population, was developed in 1950 by Raymond B. Cattell(1905) and his colleagues, who conducted a sophisticated mathematical analysis of many personality traits into a profile of sixteen basic personality "factors".