AGE SCALE -- Mental test possessing items grouped by the average performance of particular age groups. A person's performance is then compared with the average score for a particular age. The Stanford Binet was originally such a test.

BIOLOGY -- study of living things; subfields are botany and zoology. Includes anatomy, physiology, cytology, evolution, genetics, etc.

CLASSIFICATION -- grouping of phenomena into like categories and differentiated from other similar objects. Similarities are observed and, through inductive reasoning, a generalization results.

CORRELATIONAL STUDIES -- designed to demonstrate predictable and systematic variation between two variables. Negative correlation reflects consistency but inversion of relationships.

DESCRIPTIVE SCIENCE -- primarily classification. Purpose is to answer the question "what," not "why." Always the first and simplest stage of a science.

EDUCATIONAL PSYCHOLOGY -- applied science of psychology, assisting learners and teachers by a technology of education. Developmental psychology, measurement and learning are the major subfields. G. S. Hall and Thorndike are the major founders.

EVOLUTION -- in the broadest sense, any gradual change which shows progressive development over time. Charles Darwin's theory later became known as "Darwinism."

FACTOR ANALYSIS -- statistical technique for discovering the commonalities among intercorrelation coefficients. Nothing which has not been put in can be factored out. The two major theories are those of Spearman (general) and Thurstone (group) factor theories.

FUNCTIONAL -- pertaining to anything which "works" or whose actions accomplish some purpose. Originally, a term in mathematics -- a functional equation states the relationship between two variables such that one variable is a function of, or can be predicted from, another variable. The most general statement in science is Y = fX, i.e., the dependent variable is some function of the independent variable. In psychology, of course, the statement reads R = fS, 0. Behavior is predicted from what is known about stimulus and organismic variables.

GROUP TEST -- a test designed for and standardized by administering the test to a large group of persons, all at the same time. The first such test was the Army Alpha, designed by Yerkes and a committee for the purpose of screening World War I recruits.

GROUP FACTOR -- a factor accounting for the high intercorrelation of a group of items on a test and the low correlation between those items and other items outside the group. Thurstone introduced the concept as an alternative to "general factor".

POINT SCALE TEST -- a technique devised by Yerkes and others for scoring tests. Points could thus be compared with the norm points for any particular group. Wechsler adopted this system in his intelligence tests.

RELIABILITY -- consistency with which a test yields the same score, although the score may or may not have any meaning. Reliability is a necessary but not a sufficient condition for test validity.

TAXONOMY -- classification of plants or animals. There are various systems of classification, each depending upon the investigator's preference.

TWO FACTOR THEORY -- Spearman's description of intelligence -- a "g" general factor and an "s" specific factor. His factor analysis yields a comprehensive factor, running through all the test items, and a residual or specific factor, characteristic of each individual item.

VALIDITY -- the degree to which a test predicts, is correlated with, some independent criterion measure. This is predictive validity. Content and construct validity are based more on analysis of the test rather than empirical evidence. A valid test is one that is good for something and which has already been demonstrated to be reliable.

VARIATION -- the major issue in individual differences. How individuals and groups vary and why they do is the subject of descriptive psychology.


Binet, Alfred McDougall,William
Cattell, James McKeen Pearson,Karl
Darwin, Charles Spearman, Charles
Darwin, Erasmus Spencer,Herbert
Dewey, John Terman,Lewis
Freud, Sigmund Thurstone, Louis
Galton, Sir Francis Wechsler, David
Hall, G. Stanley Wundt,Wilhelm
James, William Yerkes,Robert