A Guilty Conscience Makes Us Punish Ourselves and Others

For today, I present a pair of articles on the effects of guilt. First up is Robin Hanson:

A psych study asked people to think of someone they felt guilty toward, or made them imagine feeling guilty toward someone (e.g., slacking off on a joint project, or being careless with something borrowed). Researchers then had these guilty folks divide up money between themselves, the victim, and a third party (e.g., a deserving charity or random person). Compared to controlled conditions, such people give more money to the victim, but at the expense of the third party, not themselves.

Next, a study (gated paper, press release) published in Psychological Science:

When reminded of an immoral deed, people are motivated to experience physical pain. Participants who wrote about an unethical behavior not only held their hands in ice water longer but also rated the experience as more painful than did participants who wrote about an everyday interaction. Critically, experiencing pain reduced people’s feelings of guilt, and the effect of the painful task on ratings of guilt was greater than the effect of a similar but non painful task.

I wonder at these two expressions of guilty feelings. Under what conditions do we choose to punish ourselves versus punishing innocent others?