Dr. Stanislav Grof's essay "Mind, Nature and Consciousness" provides a very lucid introduction to this theory (http://www.stanislavgrof.com/wp-content/uploads/pdf/Gregory_...):
"The basic idea of Gregory Bateson's theory of schizophrenia is that this disorder basically represents a breakdown of metacommunication [messages about messages, indicating how the communication should be understood, i.e. a wink to indicate that this is a joke, /s for sarcasm, etc]. Psychogenetically, this problem can than be traced to a specific disturbance in the communication between the mother and the future schizophrenic which involves what he called a "double bind.”
The basic characteristics of this situation are the following:
1. The child is in a relationship of vital dependency, where it is critical to identify correctly the communication from the mother.
2. He or she is receiving from the mother messages which are contradictory, since the qualifying metacommunication denies the verbal content or is otherwise incompatible with it.
3. The child does not have the opportunity to ask questions to clarify the communication.
4. The child cannot leave the field. Under these circumstances, he or she is forced to distort his or her perception of the outer world and of the inner feelings, and is incapable to develop meta-communicational skills.
Gregory's favorite example was a situation in which a mother, annoyed by a child who is active and noisy, tries to get rid of him by saying: "Darling, it is very late and you must be terribly tired; mommy will put you to bed. You know I mean well for you." The message misrepresents the truth about the matter. It says "you are tired and need to sleep" instead of "I really need some space for myself." Messages and situations of this type force the child to deny or disregard his or her inner clues and accept what the mother is saying.
Metacommunication is extremely important in human communication and individuals who do not master it tend to have great interpersonal difficulties. Metacommunicationally inept persons who are incapable to read subtle signals, understand jokes, and decode hidden meanings become easily victims and scapegoats of their peers. There has been much discussion, whether this mechanism is sufficient to explain serious psychopathology encountered in schizophrenic patients. Gregory Bateson himself believed that much of schizophrenic symptomatology can be understood as a total breakdown of metacommunication."