Altruism is any behavior aimed at improving the welfare of another individual. Altruistic behaviors include donating money, time, blood, bone marrow, and organs and kidneys to help others. Dr. Abigail Marsh, Professor in the Department of Psychology and the Interdisciplinary Neuroscience Program at Georgetown University conducts research aimed at understanding why people will undergo risks and make sacrifices to help others, even strangers. Dr. Marsh  received a PhD in Social Psychology from Harvard University in 2004 and afterward conducted post-doctoral research at the National Institute of Mental Health. Currently she directs the Laboratory on Social & Affective Neuroscience, in which research is aimed at addressing questions that include: How do people understand what others think and feel? What drives us to help other people? What prevents us from harming them? She studies this using multiple approaches that include functional and structural brain imaging in adolescents and adults from both typical and special populations, as well as behavioral, cognitive, genetic, and pharmacological methods. Dr. Marsh is interviewed by journalist David Freed.