The fact that a dying cancer cell sends out suicide signals to other cells has been dubbed the bystander effect.

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Research by Princeton psychologist John Darley, who pioneered the study of the bystander effect, has found no clear personality profile distinguishes the upstanders from the bystanders.

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In their own extensive analysis of what makes a hero, psychologists Zeno Franco and Philip Zimbardo suggest that people who don't succumb to the bystander effect are sometimes people who generally don't adhere to social norms and conventions.

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