Thorndike summarized many of his observations with his famous laws of exercise and effect. According to his law of exercise, the strength of an association varies with the frequency of its occurrence. His original law of effect stated that if an association is followed by a positive experience, it is strengthened, whereas if an association is followed by a negative experience, it is weakened. In 1929 Thorndike revised his theory by discarding the law of exercise and salvaging only the half of the law of effect that said positive consequences strengthen an association. Negative consequences, he found, have no effect on an association. Thorndike opposed the old “mental muscle” explanation of the transfer of training, which was an outgrowth of faculty psychology. Thorndike contended that learning would transfer from one situation to another to the degree that the two situations were similar or had common elements. Many of Thorndike’s ideas are found in the contemporary work of Skinnerians. Unlike structuralism, which faded away as a school because most of its findings and methodologies were rejected, functionalism lost its distinctiveness as a school because most of its major tenets were assimilated into all forms of psychology.