One passage, labeled with a white card, contained a reward while the other one, labeled with a black card, led to an electrical shock.

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James White, the Harris County, Texas, emergency management coordinator, said that most of the dead had drowned, but that two had died of electrical shock.

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It tested what would happen if a person in a position of authority ordered a subject to deliver a 400-volt electrical shock to another person, would the subject follow orders?

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The cause in about half the cases is ventricular fibrillation, an electrical disturbance in the heart that is most responsive to a shock from an AED.

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