Pendulum in psychology
For searching water, oil, lost things and missing people is accepted to use vine or pendulum. Thus it is possible to diagnose the condition of plants, animals or people. Pendulum is a great tool and it is surprising, that only some people use it. 
Pendulum - is a small sinker suspended on a thread, chain or cord. Some people as pendulum often use their wedding ring hanging on a thread.
Ideal pendulum weighs around eighty grams, easy on the eyes and convenient in use. The simplest pendulums are circular in shape and sharpened downward, they are usually well-balanced and high sensitivity. Length of the thread or chain must be ten or twelve centimeters but some prefer longer length.
Most people hold the pendulum in the hand by what they write. But it is worth experimenting, take the pendulum in the other hand, maybe you feel it more comfortable.
Sit down to the desk. Elbow of the hand in which you hold the pendulum should be based on the desk. Keep the thread or chain of the pendulum between the thumb and index fingers, palm is faced down. Feet are completely palced on the floor. The pendulum should be positioned at distance of thirty centimeters away from you.
Start to gently shake the pendulum from side to side to get used to its movements. Shake it in various directions, then start to describe circles clockwise and vice versa. Try whether its comfortable for you to hold the pendulum and whether you need to change the length of the thread.
When you will get used to the movements of the pendulum, stop it with your free hand. Then ask what the motion of the pendulum will mean a positive response. You can ask the question out loud or silently. If you have never before worked with a pendulum, it may take few minutes before you'll receive an answer. When the pendulum will give you a positive answer, stop its motion with your free hand and ask what movement will mean a negative answer. Then ask it about the responses meaning "I do not know" and "I do not want to answer."
Now when you have four possible answers, you can begin to ask the pendulum a questions. Start with questions, the answers to which are known for you. You may ask, for example: "Am i a man?" If you are man, you will get a positive response, otherwise the pendulum will give a negative answer. Ask simple questions about your age, occupation, marital status, number of children and so on.
The purpose of these questions is to give you an opportunity to get used to working with a pendulum and to demonstrate its accuracy. Then you can ask questions, the answers to which you will know later. Again you will make sure that the pendulum is extremely accurate tool.
However, there is one condition. If you are very interested in the result, your subconscious mind will affect the pendulum by controlling it and giving the answer which you want to receive. 
If, for example, somebody from the familiar to you women is pregnant, and you use a pendulum to determine the sex of the unborn child, the pendulum will give you the correct answer only, if you do not care what sex the baby will have. If you are secretly hope that the girl will be born, the pendulum will confirm this, even if its not true. 
Thus if you are interested in the result, it's better to ask other person to work with the pendulum.
You should carefully formulate a questions. The pendulum will not be able to answer the question: "What color of the car I should buy - Red or Blue?" In this case, you need to ask the question twice, asking first about one color and then about another.