Edward Thorndike

• 1. Introduction

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  Edward Lee Thorndike built one of the most influential theories in the history of psychology by watching cats try to escape from wooden boxes. Born in Williamsburg, Massachusetts in 1874, Thorndike would spend nearly his entire career at Teachers College, Columbia University, turning a simple experiment with a latch and a hungry cat into a framework that would shape how schools teach, how armies recruit, and how psychologists think about learning itself. A Review of General Psychology survey published in 2002 ranked him as the ninth-most cited psychologist of the 20th century. How does a preacher's son from a small Massachusetts town become the architect of modern educational psychology? And what happens when a scientist who changed how we understand the human mind holds beliefs that the next century would find deeply troubling?

• 2. A Preacher's Son Finds Science

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  Edward R. Thorndike was a Methodist minister in Lowell, Massachusetts, and his son Edward graduated from The Roxbury Latin School in West Roxbury in 1891. From there, he took a path through Wesleyan University, where he earned a B.S. in 1895, and then to Harvard, where he earned an M.A. in 1897. At Harvard, his curiosity landed on the question of how animals learn, and he worked closely with William James. That partnership would redirect his life. After Harvard, Thorndike completed his PhD at Columbia University in 1898 under James McKeen Cattell, one of the founding fathers of psychometrics, and his doctoral dissertation on associative processes in animals was the first in psychology to use non-human subjects. His two brothers were also scholars of note. Lynn became a medievalist specializing in the history of science and magic, while Ashley became an authority on Shakespeare. Edward's intellectual world was shaped by a family that took knowledge seriously, and he arrived at Columbia ready to take that seriousness into the laboratory.

• 3. The Puzzle Box

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  Thorndike's famous puzzle boxes were approximately 20 inches long, 15 inches wide, and 12 inches tall, each designed so that a cat pressing a bar or pulling a lever inside would trip a string over a pulley and swing open a door. His doctoral dissertation, which he titled "Animal Intelligence: An Experimental Study of the Associative Processes in Animals," grew directly from these devices. He was driven partly by frustration with prior work on animal minds: "In the first place, most of the books do not give us a psychology, but rather a eulogy of animals. They have all been about animal intelligence, never about animal stupidity." He placed cats inside the boxes and recorded not whether they eventually escaped, but how long it took each time. When he let cats observe other animals escaping, and then placed the observers inside, he found no difference in their rate of learning. Placing the cats' paws directly on the correct levers also produced no improvement. What he observed instead was that after accidentally tripping the switch once, cats pressed it faster and faster in each successive trial, producing a characteristic s-shaped learning curve. The curve showed gradual improvement, not sudden insight, which convinced him that animals learn through trial and error rather than reasoning. The learning curve also suggested that different species learn in the same way, differing only in speed.

• 4. The Law of Effect

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  From the puzzle box results, Thorndike constructed what he called the law of effect: behaviors followed by a satisfying state of affairs are strengthened, while behaviors followed by an annoying state of affairs are weakened. He also stated that the satisfaction must come immediately after the success, or the lesson would not take hold. Early in his career, he treated dissatisfaction from failure as equally powerful to the reward of success. His later research on humans led him to revise that view sharply. By 1929, he publicly acknowledged that he had been wrong about parts of his framework. He denounced the law of exercise entirely after finding that practice alone did not strengthen an association and that time alone did not weaken one. He also discarded half of the law of effect after finding that punishment is not effective in modifying behavior, while a satisfying outcome does genuinely strengthen an association. The revised law formed the conceptual bridge between his early animal research and the classroom practices that came after. The terms he used, "satisfying" and "annoying" outcomes, would later be relabeled by others as reinforcers and punishers, a vocabulary that B.F. Skinner would make famous.

• 5. Psychology Into the Classroom

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  Thorndike began his teaching career in 1899, after an unhappy year at the College for Women of Case Western Reserve in Cleveland, Ohio. He joined Teachers College at Columbia as an instructor and never left. His work there combined learning theory, psychometrics, and applied research in a way that was unusual for his time, and it shaped education in concrete, practical ways. He composed three word books to guide reading instruction: The Teacher's Word Book in 1921, a second volume covering the twenty thousand most frequent words in children's reading published in 1932, and The Teacher's Word Book of 30,000 Words in 1944. In the preface to the third book, he wrote that the list "tells anyone who wishes to know whether to use a word in writing, speaking, or teaching how common the word is in standard English reading matter." His sources ranged from Black Beauty and Little Women to the United States Constitution, the Bible, Shakespeare, and mail-order catalogues. Thorndike also opposed the prevailing view that learning should follow the natural development of the child, arguing instead that schooling should actively improve upon nature. He brought a statistical approach to educational problems at a time when most of his peers were not doing so, and he pushed for the mass marketing of tests and textbooks.

• 6. Influence and Controversy

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  During World War I, Thorndike contributed to the development of the Army Beta test, used to evaluate illiterate, unschooled, and non-English-speaking recruits. He served as president of the American Psychological Association in 1912 and was elected a Fellow of the American Statistical Association in 1917, the same year he was admitted to the National Academy of Sciences. In 1934 he was elected president of the American Association for the Advancement of Science. He was also a proponent of eugenics, arguing that selective breeding could improve human capacity to learn and maintain mental health. He wrote: "There is no more certain and economical a way to improve man's environment as to improve his nature." He also argued that differences between men and women in parental behavior were biological rather than cultural, and he described women as by "original nature submissive to men in general." His contemporary John B. Watson directly challenged this view, arguing from observations of first-time mothers that the very behaviors Thorndike attributed to instinct were performed with difficulty and therefore must have been learned. In 2020, amid the George Floyd protests, the Board of Trustees of Teachers' College in New York voted unanimously to remove Thorndike's name from Thorndike Hall, citing his racist, sexist, and antisemitic beliefs. His connectionism has also drawn criticism for being too simplistic and reductionistic, with the law of effect challenged on four fronts: its implied retroactive working, its philosophical implications, the identification of conditions that cause learning, and its practical usefulness as a general theory.

• 7. A Legacy Passed Forward

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  Clark Hull synthesized the learning theories of Thorndike and Ivan Pavlov, building on both to develop his own account of motivation and behavior. B.F. Skinner, who like Thorndike placed animals in boxes and observed what they could learn, would take Thorndike's framework on reinforcement and extend it into the dominant strand of 20th-century behaviorism. Thorndike also influenced Gestalt psychologists and researchers studying the conditioned reflex, who studied his work as a foundation even while moving in different directions. In 1937, Thorndike became the second president of the Psychometric Society, following Louis Leon Thurstone, who had established the society and its journal Psychometrika the previous year. His research drove comparative psychology for roughly fifty years. His daughter Frances, one of the five children he and Elizabeth Moulton had after their marriage on the 29th of August 1900, became a mathematician.