In the 1880s, James wanted to apply scientific methodology to mind-reading and “spiritualism.” He could not find collaborators in the Harvard academic community, but in England at that time both Alfred Russell Wallace, who had discovered the theory of evolution at the same time as Charles Darwin, and the moral philosopher Henry Sidgwick (1838–1900) and his wife, Nora, were already interested in subjects of this sort. James became part of a group of intellectuals who went to séances and carefully investigated reports of supernatural events. They also counted reports of “apparitions” that occurred on the same day the person, whose apparition appeared, had died.

This so-called “Census of Hallucinations” resulted in a statistically significant correlation between day of death and appearance of that person’s ghost. However, James thought that the sample of 17,000 would have yielded more reliable results if it were 50,000 and included American as well as British apparitions. James was also very skeptical of the table rapping and spirit-directed writing that were routine at séances, and he wanted to exclude mediums from the ranks of reputable spiritual researchers.