ment of error from the expectation of the experimenter was eliminated, it was quickly shown that the contractions were entirely subjective. Mr. Edison, I may say, is not only an inventor of phenomenal genius, but likewise a skilled and practiced experimentalist, and, as I found when making these and similar investigations with him, extraordinarily fertile in resources of method and device for wresting the secrets from nature, and usually alert against subtile sources of error; but, when drawn into the province of the involuntary life, he found himself, like men of science in general, insufficiently equipped with knowledge to even surmise, not to say provide for, the errors that may arise from the unconscious or involuntary action of mind on body.
In some instances the reverse mistake is made, and phenomena of the involuntary life are supposed to be volitional. In the case of the "Maine jumpers" or so-called "jumping Frenchmen" of Canada and the Maine woods—the incredible performances of which I have elsewhere described—it had for years been assumed, both by men of science and by the laity, that the movements were intentional, and within control. This conclusion, though most erroneous, was quite a natural one for those who have no knowledge of the relation of mind to its physical substratum.
An illustration of the second method of deception—doing nothing when the subject supposes we are doing something—is professing to apply electricity, putting the electrodes in position, and going through the motions, when no current is running, or when the connection is broken; in this way I have several times proved that patients were mistaken in inferring that electrical applications injured them; and, conversely, I have been able in one striking case to prove that the patient was right, and that a certain symptom was temporarily aggravated by the application.
Third Source of Error: Intentional deception on the part of the, subject.—This element of error is so obvious that it would seem to be quite needless to refer to it; and yet it is constantly overlooked even in researches conducted by physiologists. To assume, as is often or usually done, that the subject on whom the experiment is made is honest in his relation to that experiment, because he has a general character for honesty, is always unscientific; and all experiments where such assumption is made must be ruled out of science.
Intentional as well as unintentional deception on the part of the subject can only be scientifically met by deception on the part of the experimenter. The methods of deceiving already described suffice to guard against all deception on the part of the subject, whether intentional or unintentional.
It is clear proof of the non-expertness of Zöllner, Wallace, Charcot, and Westphal, that in their published accounts of experiments with living human beings they assumed that, if the subjects were honest, the
