A meager 5 percent said that social media had a great deal of influence on their purchasing decisions.
This comes on the heels of another study showing that brand engagement has been plummeting on Facebook over the last year, and that the company is debating charging people to promote their content.
A spokesperson for Facebook said: "The only thing this poll shows is that self reported behavioral data is unreliable. For decades, studies that look at people's actual, real-world behavior have shown that ads on all mediums, including social media, effect the things people buy."
A spokesperson for Twitter did not respond to a request for comment.
Gallup's results were based on a web and mail study of 18,525 adults, aged 18 and older, that was conducted between December 2012 and January 2013. The study does not break out influence by platform.
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