Because the act of suffering for the benefit of others goes against the evolutionary idea of survival of the fittest, there is much debate over why humans regularly go out of their way and at time jeopardize themselves for others with whom they have no relationship. The main debate is over whether people have the capacity to help others out of sheer altruist empathy or if there is always some kind of ego-driven motivation behind their actions.
Psychologist Robert Cialdini describes three different "vicarious emotional responses" people have when faced with a situation where their help is called for. These emotional responses are reflexive distress, normative distress, and sadness.
According to Cialdini, reflexive distress is characterized by "a kind of self-oriented, highly aversive, arousal-based affective state that results from exposure to cues of pain or suffering from a victim". A person experiencing reflexive distress will seek to relieve this feeling in the quickest and easiest way possible (Piliavin, Dovidio, Gaertner, Clark 1981) which will usually result in helping the person who is suffering.
Normative distress refers to the discomfort one experiences when violating a social norm. In our society helping the needing is regarded in a positive light while failing to help is seen as negative. (Berkowitz & Daniels 1964; Gouldner 1960) An observer of someone in need would therefore offer aid in order to feel that they are doing what is generally thought to be the right thing.
The last emotional response someone might experience in the presence of the needy is the negative state of sadness. Because helping has proven to have a mood enhancing affect on the average, normally socialized adult, the observer will want to help in order to alleviate their sadness. (Cialdini, Kendrick & Baumann 1982)
Regardless of the scenario, the person giving help benefits by relieving his or her self of the negative emotions brought on by witnessing a person in need.