The means of inducing hypnosis are many and varied, but they all consist in shoving aside extraneous thoughts and stimuli, and getting the subject into a quiet, receptive attitude, with attention sharply focussed upon the operator.
When the subject is in this state, the "suggestions" of the operator are accepted with less criticism and resistance than in the fully waking state. In deep hypnosis, gross illusions and even hallucinations can be produced. The operator hands the subject a bottle of ammonia, with the assurance that it is the perfume of roses, and the subject smells of it with every appearance of enjoyment. The operator points to what he says is a statue of Apollo in the corner, and the subject apparently sees one there.
Loss of sensation can also be suggested and accepted. Being assured that his hand has lost its sensation and cannot feel a pin prick, the subject allows his hand to be pricked with no sign of pain. Paralysis of the arm or leg can be similarly suggested and accepted.
Acts may be suggested and performed. The subject is handed a cardboard sword with the assurance that that is a sword, and directed to attack some person present, which he does with the appearance of serious intent.
Now, however, let the subject be given a real sword with the same command as before. Result--the subject wakes up! This suggestion was too much; it aroused dormant tendencies, broadened out the field of activity, and so produced the waking condition. A suggestion that runs counter to the subject's organized character and tendencies cannot get by without arousing them and so awakening the subject. Consequently, there does not seem to be much real danger of crimes being performed by innocent persons under hypnosis.
In mild hypnosis, the above striking phenomena are not produced, but suggestions of curative value may be conveyed, and so taken to heart that they produce real results. The drowsy state of a child just falling to sleep can be similarly utilized for implanting suggestions of value. One little boy had a nervous twitching of the face that was very annoying. His father, just as the child was dropping off to sleep, conveyed the suggestion that the child didn't like this twitching; and this suggestion, repeated night after night, in a few days caused the twitching almost wholly to disappear.
Suggestion often succeeds in a waking state. In a certain test for "suggestibility", the task is set of copying a series of lines. The first line is short, the second longer, the third longer still, the rest all of the same length, but the more suggestible individual keeps on making each succeeding line longer. There are, however, various tests for suggestibility, and an individual who succumbs to one does not necessarily succumb to another, so that it may be doubted whether we should baldly speak of one individual as more suggestible than another.
Suggestion may be exerted by a person, or by the circumstances. If by a person, the more "prestige" he enjoys in the estimation of the subject, the greater his power of suggestion. A prestige person is one to whom you are submissive. A child is so dependent on older people, and so much accustomed to "being told", that he is specially susceptible to prestige suggestion.