In another experiment, the volunteers were given the choice of volunteering to raise money for a sick child who could not pay his medical bills.
Some were told that they would almost certainly be asked to help -- others were told that they were unlikely to be called upon.
"Only in the latter situation was a link between religiosity and volunteering evident," the researchers said.
Image: Devotees hold a candle light vigil during an Easter Service at midnight mass in St Mary's Church in Hyderabad.
Photograph: Noah Seelam/AFP/Getty Images
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