The secret of quick thinking: The invention of mental speed in America, 1890–1925

In the early 20th century, mental speed became a dominant measure of intelligence in the United States. For both cultural and technical reasons, this had not always been the case. For 19th-century Americans, quickness of speech and thought often signified lack of self-discipline. Unlike with other objects of temporal measurement and rationalization such as factory work, little scientific or popular consensus existed over how to clock the...