In psychological research on altruism, studies often observe altruism as demonstrated through prosocial behaviors such as helping, comforting, sharing, cooperation, philanthropy, and community service. Research has found that people are most likely to help if they recognize that a person is in need and feel personal responsibility for reducing the person's distress. Research also suggests that the number of bystanders witnessing distress or suffering affects the likelihood of helping (the "Bystander effect"). Greater numbers of bystanders decrease individual feelings of responsibility. However, a witness with a high level of empathic concern is likely to assume personal responsibility entirely regardless of the number of bystanders.