paired with the color, to be remembered, on a reappearance of the given color". A series of Calkins' experiments under Hugo Münsterberg, taking place between 1894 and 1896, was concerned with the concept of recency as it relates to a person's ability to remember something. Her paired-associates technique showed that recency yields to the vividness, and both vividness and recency yields to frequency. Her method consisted of showing a series of colors paired with numerals, followed by testing for recall of the numbers when the colors with which they were previously paired are flashed again. The findings of her study revealed that numbers paired with bright colors were retained better than those associated with neutral colors. Yet, the prime factor influencing memory was not color but the frequency of exposure. Calkins described the technical memorizing method that she used, known as paired-associations, as even more significant than the results of the experiment. The formula where a subject is presented with a stimulus and asked to provide the appropriate response became a standard tool for studying human learning. Although Georg Elias Müller criticized her method, he refined and adopted it, calling it () and it has been widely used ever since. Edward B. Titchener included her research in his Student's Manual, and in her autobiography, Calkins refers to a Professor Kline who selected the paired-associates method for his textbook, Psychology By Experiment. The paired-associates technique was also included in psychology textbooks published by Herrnstein and Boring. Although the paired-associates technique is regarded as one of Calkins' biggest contributions to psychology, Calkins herself did not attach very much importance to this work. It is suggested that, despite Calkins often downplaying the memory implications of her research, her writings "constitute a truly remarkable legacy ... [they] represent important, basic, replicable phenomena that are fundamentally important." Her study on paired associates learning under Münsterberg constituted her doctoral dissertation which was published in 1896. Harvard refused to approve the unanimous recommendation of the Department of Philosophy and Psychology to grant Calkins her doctoral degree. Eliot believed strongly that the two sexes should be educated separately and, although he allowed Calkins to be a "guest," he and the rest of the board refused to grant her the degree. Calkins had completed all of the requirements for the Ph.D., including passing exams and completing a dissertation, and all of her Harvard professors had recommended her for the