“Cold reading” and “hot reading” are two techniques used by psychics, mentalists, and various phonies to appear to read minds and otherwise know things that they could not possibly know. Whether you realized it or not, you have seen both of these techniques at work. Here is the difference:
Cold Reading Techniques: No Preparation Needed
Cold readings are encounters in which a purported psychic takes a subject cold (i.e., without any advance preparation). Any real information a psychic obtains about the subject must come from the subject, because there is no other source for that information. The psychic can, however, pretend to have information by (a) making statements about the subject that would be true of virtually anyone and (b) making high-probability guesses.
For example, a psychic might say, “You have always wanted to write a book, but have never gotten around to it.” That is a so-called Barnum statement — a statement that is true of the vast majority of people. When a subject hears such a statement, he/she is typically impressed by its accuracy. Another cold reading technique would be to make a high-probability guess; for example, the psychic might say, “There is someone important in your life whose name begins with the letter J.” Because many common names start with J, there is a good chance that this prediction is true. For more on cold reading techniques, see the Wikipedia entry: http://en.wikipedia.org/wiki/Cold_reading.
Hot Reading Techniques: First, Do Your Homework
As the name implies, hot reading techniques are the opposite of cold reading techniques. When a hot reading occurs, the purported psychic already has knowledge about the subject. Think, for example, of the phony televangelist in the move Fletch Lives. The televangelist’s staff members collected data about the people in his audience; then, when an audience member was called on to the stage by the televangelist, the staff members read information about that audience member into a microphone. The televangelist listened to the information via an earpiece and then pretended to prophesy about the audience members.
Thanks to improvements in technology, hot reading has become easy. If a phony psychic knows in advance the identity of a subject, he/she can search the internet to find information about the person. Traditional data gathering via confederates in an audience are still used effectively, as well. And, of course, hot reading can be used in conjunction with the principles of cold reading. For more on hot reading techniques, see the Wikipedia entry here.