A double bind is a dilemma in communication in which an individual (or group) receives two or more reciprocally conflicting messages. In some scenarios (e.g. within families or romantic relationships) this can be emotionally distressing, creating a situation in which a successful response to one message results in a failed response to the other (and vice versa), such that the person responding will automatically be perceived as in the wrong, no matter how they respond. This double bind prevents the person from either resolving the underlying dilemma or opting out of the situation. Double bind theory was first stated by Gregory Bateson and his colleagues in the 1950s, in a theory on the origins of schizophrenia and post-traumatic stress disorder. Double binds are often utilized as a form of control without open coercion—the use of confusion makes them difficult both to respond to and to resist. A double bind generally includes different levels of abstraction in the order of messages and these messages can either be stated explicitly or implicitly within the context of the situation, or they can be conveyed by tone of voice or body language. Further complications arise when frequent double binds are part of an ongoing relationship to which the person or group is committed. The double bind is often misunderstood to be a simple contradictory situation, where the subject is trapped by two conflicting demands. While it is true that the core of the double bind is two conflicting demands, the difference lies in how they are imposed upon the subject, what the subject's understanding of the situation is, and who (or what) imposes these demands upon the subject. Unlike the usual no-win situation, the subject has difficulty in defining the exact nature of the paradoxical situation in which they are caught. The contradiction may be unexpressed in its immediate context and therefore invisible to external observers, only becoming evident when a prior communication is considered.