i88i.] Physiology of Mind- Reading. 417 
guarded against if the results are to have any precise and 
authoritative value in science. 
1. The involuntary and unconscious action of brain and 
muscle, including trance, in which the subject becomes a 
pure automaton. I have used the phrase “ involuntary life” 
to cover all these phenomena of the system that appear 
independently of the will. The majority of those who studied 
the subject of mind-reading — even physicians and physio- 
logists — failed through want of a proper understanding or 
appreciation of this side of physiology. 
2. Chance and coincidences. Neglect of this source of 
error was the main cause of the unfortunate results of the 
wire and chain experiments with mind-readers. 
3. Intentional deception on the part of the subject. 
4. Unintentional deception on the part of the subject. 
5. Collusion of confederates. To guard against all the 
above sources of error it is necessary for the experimenter 
himself to use deception. 
6. Unintentional assistance of audience or bystanders. 
When the muscle-reader performs before an enthusiastic 
audience, he is likely to be loudly applauded after each suc- 
cess ; and, if the excitement be great, the applause, with 
shuffling and rustling, may begin before he reaches the right 
locality, while he is approaching it ; when, on the other 
hand, he is far away from the locality, the audience will 
inform him by ominous silence. The performance thus 
becomes like the hide-and-seek games of children, where 
they cry “ Warm !” as the blindfolded operator approaches 
the hidden object ; “ Hot !” as he comes close to it ; and 
“ Cold !” when he wanders far from it. Some of the appa- 
rent successes with the wire-test may be thus explained. 
In regard to all the public exhibitions of muscle-readers, 
it should be considered that the excitement and eclat of the 
occasion contribute not a little to the success of the operator ; 
the subjects grow enthusiastic — are partly entranced, it may 
be — become partners in the cause of the performer — and 
unconsciously aid him far more than they would do in a 
similar entertainment that was purely private. In a private 
entertainment of muscle-reading at which I was present, one 
of the subjects, while standing still, with his hands on the 
operator, actually took a step forward toward the locality 
on which his mind was concentrated, thus illustrating in a 
visible manner the process by which muscle-reading is made 
possible. 
The subject under discussion, it will be observed, is to be 
studied both inductively and deductively. The general claim 
