Increased numbers of psychiatric diagnoses and increased levels of psychological distress are seen in the majority of medical clinic patients with gastrointestinal motility disorders. In IBS, psychological symptoms are believed to be comorbid conditions, which do not cause the motility disorder but which do influence the patient's decision to consult a physician. In functional dyspepsia, psychological symptoms are present in many patients, but their role is not known; the available data suggest that psychological symptoms do not predict which patients will consult a physician. Among constipated patients, anxiety is believed to contribute to the development and course of pelvic floor dyssynergia by increasing pelvic floor muscle tension. Constipated patients without physiologic abnormalities to explain their constipation appear to have more psychological symptoms than those with delayed colonic transit, but there is significant psychological distress even in patients with slow transit constipation. Psychological symptoms do not seem to predict which constipated patients will consult a physician. There is an increased incidence of psychiatric diagnoses in patients with esophageal motility disorders as well, but the role that these psychological symptoms play in the course of the disorder is not known. Patients with the most common gastrointestinal motility disorders, IBS and dyspepsia, report experiencing more stressful life events, and IBS patients appear to show a greater increase in gastrointestinal symptoms when exposed to stressors. Laboratory studies document that acute psychological stressors do alter gastric, small bowel, and colonic motility, and patients with IBS appear to show a greater change in colonic and ileal motility with stress than healthy controls. Greater reactivity has not been demonstrated for the esophagus or stomach, however, and it has not been demonstrated for other gastrointestinal motility disorders. A characteristic of many patients who consult gastroenterologists for IBS and other motility disorders is a tendency to report multiple somatic complaints (including many nongastrointestinal complaints) and to overuse medical resources. This pattern of behavior is referred to as somatization or abnormal illness behavior. One source of abnormal illness behavior is childhood social learning, which occurs (1) when parents provide gifts or special privileges to a child who reports somatic symptoms or (2) when parents model abnormal illness behaviors themselves.