Thorndike, Edward Lee (1874-1949), a United States psychologist and educator who was a pioneer in educational psychology. He insisted that educational practices should be based on results of investigations of the learning process. Thorndike wrote many books on various phases of psychology and education. The most influential was Educational Psychology (1903; expanded into 3 volumes, 1913-14), a standard work for many years.

Thorndike was one of the first to develop standardized intelligence, achievement, and aptitude tests. He helped devise tests that were used during World War I for classification of army personnel. His word lists giving the frequency with which various words appear in newspapers, correspondence, etc., became widely used by people writing books for specific age and grade levels. The Thorndike-Barnhart dictionary series, edited by Clarence L. Barnhart, is based on Thorndike's principles.

Thorndike was born in Williamsburg, Massachusetts. He was educated at Wesleyan, Harvard, and Columbia universities, receiving his doctorate from Columbia in 1898. He taught at Western Reserve University, 1898-99, and Columbia, 1899-1940.