Being excluded doesn\'t leave physical bruises but it can cause deeper pain that lasts longer than a physical injury, U.S. researchers say. Kipling D. Williams, a professor of psychological sciences at Purdue University, says when a person is ostracized, the brain\'s dorsal anterior cingulate cortex, which registers physical pain, also feels social injury. The process of ostracism includes three stages -- the initial acts of being ignored or excluded, coping and resignation. Williams says. \"Being excluded by high school friends, office colleagues, or even spouses or family members can be excruciating,\" Williams says in a statement. \"And because ostracism is experienced in three stages, the life of those painful feelings can be extended for the long term. People and clinicians need to be aware of this so they can avoid depression or other negative experiences.\" Williams designed studies that involved more than 5,000 people using a computer and found that two or three minutes of ostracism can produce lingering negative feelings. \"Being excluded is painful because it threatens fundamental human needs, such as belonging and self-esteem,\" Williams says. \"Again and again research has found that strong, harmful reactions are possible even when ostracized by a stranger or for a short amount of time.\" The findings are published in the journal of Current Directions in Psychological Sciences.