In 1886 Wolfe published his doctoral thesis on tonal memory. Wolfe chose to investigate retention by the method of recognition, a method that requires a stimulus to be present and the subject to make a judgment about the stimulus. This paradigm lends itself well to psychophysical methods which are what Wolfe used in his research on memory for tones. He believed that recognition memory was a simpler and more basic memory process that recognized objects or events as familiar or unfamiliar.