particularly complex or intense. Symptom coherence Symptom coherence is defined by Ecker and Hulley as follows: A person produces a particular symptom because, despite the suffering it entails, the symptom is compellingly necessary to have, according to at least one unconscious, nonverbal, emotionally potent schema or construction of reality. Each symptom-requiring construction is cogent—a sensible, meaningful, well-knit, well-defined schema that was formed adaptively in response to earlier experiences and is still carried and applied in the present. The person ceases producing the symptom as soon as there no longer exists any construction of reality in which the symptom is necessary to have. There are several forms of symptom coherence. Some symptoms are necessary because they serve a crucial function (such as depression that protects against feeling and expressing anger), while others have no function but are necessary in the sense of being an inevitable effect, or by-product, caused by some other adaptive, coherent but unconscious response (such as depression resulting from isolation, which itself is a strategy for feeling safe). Both functional and functionless symptoms are coherent, according to the client's own material. In other words, the theory states that symptoms are produced by how the individual strives, without conscious awareness, to carry out self-protecting or self-affirming purposes formed in the course of living. This model of symptom production fits into the broader category of psychological constructivism, which views the person as having profound, if unrecognized, agency in shaping experience and behavior. Symptom coherence does not apply to those symptoms that are not directly or indirectly caused by implicit schemas or emotional learnings—for example, hypothyroidism-induced depression, autism, and biochemical addiction. Hierarchical organization of constructs As a tool for identifying all of a person's relevant schemas or constructions of reality, Ecker and Hulley defined several logically hierarchical domains or orders of construction (inspired by Gregory Bateson): The first order consists of a person's overt responses: thoughts, feelings, and behaviors. The second order consists of the person's specific meaning of the concrete situation to which they are responding. The third order consists of the person's broad purposes and strategies for construing that specific meaning (teleology). The fourth order consists of the person's general meaning of the nature of self, others, and the world (ontology). The fifth order consists of the person's broad purposes and strategies for construing that general meaning. Higher orders (beyond the fifth order) are rarely involved in psychotherapy. A