A way of testing a individual's claim of possessing certain mental abilities. A book is used to ensure the test is repeatable under the same conditions each time it is undertaken.
A typical test would involve an examiner (tester), a participant (volunteer) and the person undergoing testing (subject). The participant will be instructed by the examiner to concentrate on a word, or phrase, randomly selected from a book. The examiner will then test the subject in various ways, including but not limited to, testing the subject's ability to 'recall' words that only the participant has seen.
Stage performers, such as mentalists, will often replicate book-tests live on stage to test their mental abilities for the entertainment of an audience.
A very direct test of special mental ability is to have a participant open the book randomly on any page and then to pick a word at random on that page. The examiner then tests to see if the subject can demonstrate the ability to know what word was chosen, simply by concentrating on the participant's thoughts.
In other tests, the participant may be asked to read a randomly selected passage from the book. He or she, is then asked to record their feelings, inspired by the passage, in secret. The subject is then tested by the examiner to determine how accurately they can pick up on the participants recorded emotions.