Provided are a device, system, and method for treating a patient having posttraumatic stress disorder (PTSD) or other such psychiatric disorder. An event being recounted by the patient is recorded and a sensory environment of the patient is controlled so as to administer exposure therapy to the patient. Patient mental state may be monitored during administration of the exposure therapy to the patient, and the exposure therapy may be varied in correspondence to the monitored mental state of the patient. In one embodiment, hierarchy assembly means creates a treatment hierarchy based on input from the patient, and hierarchy navigation means navigates within the treatment hierarchy in response to the mental state of the patient.