Which psychological phenomenon describes individuals acting against their better judgment in group settings?

The correct choice describes deindividuation, a psychological phenomenon where individuals in group settings may lose their self-awareness and sense of personal responsibility. This can lead them to engage in behaviors that go against their better judgment, often due to the anonymity and diminished accountability felt in a crowd. Anonymity can reduce the fear of repercussions, allowing individuals to act in ways they usually wouldn't when alone or identifiable.

In contrast, conformity typically involves changing one's beliefs or behaviors to match those of a group due to real or imagined pressure. Obedience refers to following the orders or directives of an authority figure, often involving a power dynamic that drives behavior. Social facilitation describes the tendency for individuals to perform better on simple tasks when in the presence of others, which is quite different from acting against one's judgment. Thus, deindividuation is accurately representative of the phenomenon described in the question.