Robert Ladd Thorndike is most notably associated with the field of psychological measurement, and is best known for his ability to identify flaws in a test and concisely reconstruct it as a reliable instrument that yields valid results. Throughout his career, Thorndike concerned himself with the quality of testing instruments, accurate interpretation of results, and accurate application of interpretations. He advocated improved results in psychological and educational research and greater examiner responsibility for the use of data gathered from educational and psychological tests and measurements for better decision-making.

The youngest child in his family, Thorndike (22 September 1910–1990) was born in Montrose, New York to renowned psychologist Edward Lee Thorndike and his wife Elizabeth Moulton. Thorndike’s father, who studied the intelligence of animals and applied his findings to the human educational experience, shared his research in educational psychology with his children. Summers proved educational for young Thorndike as he benefited from opportunities to help with his father’s reward-punishment experiments on cats and chickens. He also helped his father compile high-frequency word lists.

Honoring his father’s suggestion that he obtain a solid foundation in mathematics before studying psychology, Thorndike received his bachelor’s degree in mathematics from Wesleyan University in 1931. His advanced math degree, coupled with his exposure during childhood to a rich background in educational psychology, contributed to his academic successes at Columbia University; where he earned master and doctorate degrees in psychology in 1932 and 1935, respectively. Before he received his Ph.D., Thorndike was named Assistant Professor in psychology at George Washington University and remained there until 1936. He then joined the Psychology Department of Teachers College, Columbia University.

During his tenure at Teachers College, Thorndike became a leading authority on psychological measures and evaluations. He used factor analysis to examine and differentiate varying abilities in the learning of rats, particularly the albino rat.

Thorndike advocated improved research by illuminating the shortcomings of aptitude and intelligence measurements. One example is his work during World War II regarding the reliability of Air Force pilot and bombardier assessment. Thorndike’s ingenuity in identifying and isolating abilities helped him illuminate the insufficient nature of performance tests and develop testing procedures that were more reliable. Such analysis attests to the “hallmarks of Thorndike’s style: identification of confusion about a fundamental topic, orderly and pioneering reconceptualization, and clear exposition” (Plucker 2002).

Thorndike also was interested in academic underachievement. He explained this phenomenon as aptitude-achievement discrepancies, which he believed resulted from the inadequacies of educators and psychologists. His analysis of underachievement revealed shortcomings inherent in testing, specifically those related to inaccurate predictions about achievement. He declared that the number of test results indicating underachievement would diminish when examiners better understand testing factors and improve their predictions about performance. Thorndike categorized aptitude-achievement discrepancies into four areas: errors of measurement, heterogeneity of criterion, scope of predictors, and variable manipulation.

An active member in major organizations devoted to making advancements in psychology, Thorndike served as President of the Psychometric Society, served on the Board of Directors of the American Psychological Association, and was president of the American Educational Research Association. He also served as a trustee of the James McKeen Cattell Fund, a foundation that supports development and beneficial application of scientific research in psychology.

Thorndike initiated the restandardization of the fourth edition of the Stanford-Binet Intelligence Scale, Form L-M. With colleague Irving Lorge, Thorndike coauthored the Lorge-Thorndike Intelligence Test for assessing abilities in reasoning, learning, and problem-solving, which later became the Cognitive Ability Test. The test’s four major areas (verbal reasoning, quantitative reasoning, abstract/visual reasoning, and short-term memory) are used to establish a developmental pattern in the cognitive thinking abilities of students in K–12. Thorndike spent most of the 1980s on cognitive ability research, helping to define the phenomenon, to describe its characteristics, and to develop appropriate measures for it.

Thorndike also produced an extensive resource collection thorough his numerous publications in educational journals, textbooks, and texts. His greatest contribution to the advancement of psychometrics was his encouragement of researchers to examine their own philosophies and techniques. He strived to motivate his contemporaries and to influence future colleagues in the field to adopt a concern for exactness in educational and psychological measurements.

Contributed by Aaron Adams, University of Texas at Austin

Craighead, E. W., and C. B. Nemeroff, eds. 2002. The Corsini encyclopedia of psychology and behavior science, vol. 1, 3d ed. New York: John Wiley and Sons.

Jones, L. V., and G. A. Kimble. 2002. The James McKeen Cattell Fund: A Benevolent Foundation for Psychology. Durham, N.C.: The James McKeen Cattell Fund.

Plucker, J. 2003. Robert Thorndike: 1910-1990 Psychometrician. Bloomington, Ind.: Human Intelligence Biographical Profiles.

Thorndike, R. L., and E. P. Hagan. 1986. Measurement and evaluation in psychology and education, 4th ed. New York: John Wiley and Sons.