By social media editor Melony Roy

PHILADELPHIA (CBS) — A secret psychology experiment conducted on Facebook users without their consent has sparked outrage.

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For one week in 2012, Facebook manipulated the news feeds of 689,000 users, hiding positive or negative posts to see how those users responded. The response this weekend was anger.

“It’s clearly not ethical to do what Facebook did,” says Art Caplan, Director of Medical Ethics at New York University. “You have to get people’s permission if you’re going to put them into a research project”

“They need to layout what they’re doing,” Chaplan says. “They need to explain to you that you don’t have to participate if you don’t want to since you have the right to refuse to be in any research, and they need to layout what they plan to do with the results.”

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The results were published in the March issue of the Proceedings of the National Academy of Sciences.

In a blog post, Facebook says “The reason they did this research is because they care about the emotional impact of Facebook and the people who use it.” Facebook went on to say that “their goal was to never to upset anybody.”

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