Whereas 83.5% of those participants in the study who were not shown the flag in the questionnaire said they had voted for Mr Obama, only 72.8% of those who had been shown the flag voted for him.

ECONOMIST: The Stars and Stripes may change the outcomes of elections

Soldiers are under no legal duty to give their opponents a chance to surrender, though if the white flag is shown it must usually be honoured.

ECONOMIST: Assassination

The company pounced when the South Korean flag was shown next to North Korean players on a big screen before an Olympic football game in Glasgow in July and when Chelsea's Eden Hazard clashed with a ball boy in Swansea in January, taking out newspaper ads.

WSJ: Soccer Referee Sponsorship Is Up for Grabs