The French physiologist Charles Richet introduced mathematical chance to the tests, and also discovered that telepathy occurred independent of hypnotism. Interest in telepathy increased following World War I as thousands of bereaved turned toward Spiritualism attempting to communicate with their dead loved ones. Mass telepathic experiments were undertaken in the United States and Britain. An individual is aware of the danger to the other person from a distance. Often such information causes the person, the receiver, to change is course of action, such as changing his travel plans or daily schedule, or to just call or contact the other person.
Some incidents involve apparent telepathy between humans and animals.
Telepathy seems to be related to the individual's emotional state. This is true of both the sender and receiver. Most women were receivers, as case findings showed, and one possible explanation is that women are more in touch with their emotions and rely on intuition more than men. Geriatric telepathy is fairly common, this may be due, it is speculated, to the impairment of the senses with age. Telepathy can be induced in the dream state.