n. difficult or infrequent excretion of feces. The normal frequency of human bowel movements varies from three times a day to one every 3 days. In addition to diseases and mechanical obstructions, constipation may be caused by psychogenic factors. Psychogenic constipation is observed in some individuals with obsessive-compulsive disorder who assign such importance to regularity that abnormal amounts of time and effort are devoted to daily bowel movements.