An author of what some are calling a "shady" study is apologizing today for the anxiety caused by a 700,000-person experiment polling people's emotions on Facebook.

"Having written and designed this experiment myself, I can tell you that our goal was never to upset anyone," Adam Kramer, who works for Facebook and is one of three authors of the PNAS study, wrote in a statement sent to ABC News. "I can understand why some people have concerns about it, and my coauthors and I are very sorry for the way the paper described the research and any anxiety it caused."

Over the course of one week, the experiment conducted in early 2012 exposed 700,000 random Facebook users to both negative and positive triggers to test their emotional reaction.

They concluded that positive posts caused people to be happier and negative posts caused people to be sadder, aka: proof of an "emotional contagion."

"These results indicate that emotions expressed by others on Facebook influence our own emotions, constituting experimental evidence for massive-scale contagion via social networks," according to the study.

Reactions across social media today had some users questioning the ethics of the study and others calling it "shady."

Facebook operates shady experiments with their users: surprised?! http://t.co/IsDE18pxKZ

- Frank Bauer (@BauersFrank) June 30, 2014

The more I learn the more pissed I am. #Facebook study not only IRB approved & PNAS accepted but US Army funded: http://t.co/8AJoga8C2v #WTF

- Khadijah M. Britton (@KMBTweets) June 29, 2014

Did you dump your boy/girlfriend, kick the dog, quit a job because Facebook toyed with your emotions? Ethics/Morals? http://t.co/K7eGxJyNQf

- Graham Rogers (@extensions_th) June 30, 2014

But Kramer said the goal of the research was just to learn how to provide a better service to Facebook users.

"The reason we did this research is because we care about the emotional impact of Facebook and the people that use our product," Kramer wrote.