(CNN) – Ever feel like all the news you read is depressing? You may be right, if you’re one of thousands who had their news feeds manipulated by Facebook.
For one week in 2012, the social media giant intentionally put upbeat posts on some of its users’ feeds and negative posts on others.
It was part of a psychological study Facebook conducted with researchers at Cornell and the University of California, San Francisco.
Many online expressed outrage after learning of the study, which focused on 690,000 users. There is no indication that the subjects were asked if they would like to take part in the study.
Once of the Facebook researchers who designed the experiment published a post on Sunday, apologizing to outraged Facebookers.
A spokesman for the company said Facebook frequently does research to improve the site’s content, and they never collect unnecessary information.
The study found people who got bad news were slightly more likely to write negative posts, while those who heard good news responded more positively.
The results of the study were published this month in the Journal Science.
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