Shapiro and Nelson (1955) suggested that an important factor in the cognitive impairment of psychiatric patients was a diminution of present learning ability. They devised a new test in which the subject had to learn and retain the meanings of five previously unknown words. Walton and Black (1957) developed this technique in their Modified Word Learning Test (MWLT). In this test, the patient is given the Terman-Merrill Vocabulary until he is unable to recall the meanings of ten consecutive words. He is then told the meanings of these ten words. If, immediately afterwards, he fails to give the definitions of at least six of them, the meanings of all ten words are given again, changing the wording to avoid rote learning.