There are very few people who cannot be influenced by suggestion to some extent; and when suggestion is scientifically applied so as to direct the imagination into certain definite channels, then it is fairly easy to produce a degree of hypnosis in almost anybody. Naturally, the best subjects will be those with a vivid imagination and intelligent enough to concentrate their mind on the suggestions of the hypnotist.

Scatter-brained people who are unable to control their thoughts and direct them into the desired channel make poor subjects, but can be improved with training. lt follows then that ordinary normal healthy people make the best subjects - the more intelligent and imaginative they are, the better.

Nervous subjects are often difficult at first, because they lack the ability to concentrate their minds and control their thoughts. Dull and stupid people or those with practically no imagination are also difficult. The insane are exceedingly difficult, and it is impossible to hypnotize an idiot.

People who boast ‘I can’t be hypnotized’ are really saying, ‘I’m a dull, stupid person with no imagination or intelligence whatsoever’; or else, ‘I am too scatter-brained to concentrate my mind.’ The fact that hypnotism deals with the imagination and not the will-power often defeats the sceptic. Secretly he believes in (or imagines) the power of hypnotism while openly he boasts of his inability to be hypnotized, in order to bolster up his courage. As a result the sceptic is often the easiest person to hypnotize, providing he complies with the general directions and does not actively resist  - although, in some cases, such resistance avails him nothing.

On the other hand, many people say they would like to be hypnotized, but secretly they believe (or imagine) that it would show they were ‘weak willed’ if they allowed themselves to go into a trance. As a result they resist involuntarily while they proclaim loudly their ardent desire for hypnosis. When the attempt fails, as it may easily do under these conditions, they profess to be greatly disappointed, but secretly rejoice, as they fondly imagine, in their ‘strong will-power’.

Another difficult type of patient is the ‘know-it-all’ sort, who is seldom at pains to conceal his contempt for hypnotism. He can usually be deflated by explaining that his method of thinking has got him where he is, and that if he wishes to lose his phobia or obsession he had better concentrate and learn to think properly.

When it has been carefully and patiently explained that it rests entirely with himself as to whether he becomes hypnotized or not, he is usually so anxious to prove that he can do anything that anyone else can do, that hypnosis can as a rule be achieved.

Very anxious and nervous people are often troublesome at first because they try too hard. Like people who grit their teeth and clench their fists while vowing they will sleep, they promptly keep themselves awake by their intense efforts.

Hypnotists are often difficult because, although they should know better, they tend to criticize the technique of the person who is endeavouring to assist them. On the other hand, mediums and others who consider themselves ‘psychic’ usually make very good subjects, as they are accustomed to inducing a state of trance by self-hypnosis.

No man is a prophet in his own country, so that relatives and close friends of the hypnotist are often difficult, as they are not impressed by someone they know so well. An example of this is found in the New Testament:

People who stutter or stammer usually make good subjects, as do those who walk or talk in their sleep.

Those who suffer from insomnia are usually difficult at first, because the very idea of ‘going to sleep’ (as they conceive the induction of the trance) is repellent to them and they fight against it involuntarily, while bewailing their inability to ‘go off’. However, in a few sessions they can be taught to relax, and usually they do very well. Alcoholics are as a rule easy to hypnotize if they really want to be cured. The man who seeks hypnosis because he realizes drink is ruining him and really wants to give it up, although he feels his will-power is not strong enough to overcome the craving, will usually make a good subject. On the other hand, if the patient is dragged along by his wife or relatives and has no real desire to give up alcohol, then hypnosis is likely to be very difficult and success highly problematical. Generally speaking, when there is a real motive for desiring hypnosis, then success is extremely probable, although, if there is great anxiety, several sessions may be required to allay this.

Apart from the general characteristics described, there are certain definite tests of susceptibility which enable the hypnotist to form a good idea of what sort of hypnotic subject the patient will make.

Stage hypnotists make great use of these tests to pick out the easiest and most susceptible subjects for their demonstrations.

One of the simplest and easiest tests is the postural sway test. The subject is told to stand erect, feet together and body rigid. While looking into the hypnotist’s eyes he is told that he is to imagine his body is like a plank of wood balanced on end. The hypnotist’s hands are placed on the shoulders and the patient is told that as the hands are withdrawn he will feel a force drawing him forward. As the hypnotist steps backwards a susceptible patient will fall forward just like a plank of wood toppling over. The hypnotist must, of course, be ready to catch the patient. If the patient is not susceptible, or deliberately resisting, he will not fall; or, if he starts to do so, will check himself by taking a step forward. Very occasionally an extremely resistant patient will fall backwards. The hypnotist must be on the look-out for this.

lf the patient is taller, so that the hypnotist cannot look in the eyes easily or if he wishes to confirm the above test, he may stand behind the patient, ask him to look at a spot on the ceiling, and then close the eyes. Again, the patient is told he will topple over backwards as the hypnotist removes the hands from his shoulders. As the hypnotist steps back, a susceptible patient will fall, stiff and rigid, into his waiting arms. Few people care to fake this test.

In another test the subject may be asked to close the eyes and told that he will begin to sway in time to music. Or again, he may be asked to imagine he is on a boat which is rolling from side to side, and the degree to which he reacts to these suggestions indicates the susceptibility of the patient.

A favourite test is the hand-clasping test. The subject is asked to clasp the hands together, fingers interlocked, and to think that his hands are firmly locked together. Further suggestions to this effect are given; and at the appropriate moment he is told that he is unable to take them apart. Certain stage performers like to make doubly certain by getting the subjects to press down on their heads with the backs of the locked hands. This tends to ‘lock’ the hands mechanically and so help the suggestion.

Still another test is to tell the subjects to close their eyes tightly, telling them that the lids are locked together and that they cannot open them. Strangely enough, if a number of people are challenged in this way there will always be some people who are unable to open their eyes.

Another test which is often useful with children, is to ask them to sit down with the outstretched arm and hand resting on the table. It is then stated that by stroking the arm, the arm and hand will get lighter and lighter and slowly lift off the table.

This will nearly always succeed, with children particularly, and serves as a useful introduction to hypnosis.

Another spectacular test is to have the subject hold a ring or similar object suspended by a thread over a circle drawn on a piece of paper. The patient is told to let his eyes travel up and down a line drawn through the centre of the circle, and that as he does so the ring will soon begin to travel up and down the line also. In fully 90 per cent. of people the ring will soon begin to sway; and further: if the direction of travel of the eyes is changed, the ring will change direction also.

An even simpler test is to place a forefinger on the patient’s hand and to ask him to imagine it is burning hot. Susceptible people will soon begin to feel a hot sensation.

There are innumerable tests such as these all depending upon similar principles, and many hypnotic practitioners set great store by them, believing that they help to impress the patients and so prepare them for hypnosis. Certainly, when successful they are impressive; but if they fail, as they may do in certain cases, then the patient is only too likely to consider that he is ‘not a good subject’. Such an attitude of mind may hinder the onset of hypnosis by the suggestion of possible failure.

Since 90%, to 95%, of patients can be hypnotized to one stage or another, and it soon becomes apparent whether they are good subjects or not by the way they respond to the hypnotic suggestions, there seems little point in wasting time with suggestibility tests. They are useful, of course, if it is desired to pick out possible good subjects from a group of volunteers for the purpose of demonstration.

Even if the subject responds to the suggestibility tests it does not necessarily mean that he will make a good hypnotic subject although, in the great majority of cases, it is usually a very good indication.

If the patient definitely resists, however, he will probably be very difficult to influence. For this reason stage hypnotists are very careful to dismiss all who fail to respond to their tests. 
Medical men with sick patients demanding cure cannot afford to pick and choose only the easiest and most susceptible patients and dismiss the rest; so that these tests, while interesting, are of less importance in medical practice.

In the author’s opinion it is simpler to avoid all these tests, and explain to the patient that hypnosis is merely a matter of concentrating the mind, and imagining what is suggested, so that the appropriate ‘feelings’ will follow.

It can be pointed out that if the patient thinks about food he can make his mouth ‘water’ just the same as if there were real food present. In the same way he will be able to get the ‘feelings’ he desires by imagining what the hypnotist suggests. People who may have doubts about their ability to be hypnotized usually feel much more confident of success when they realize that it is only a matter of using their imagination under the direction of the hypnotist.