It is being reported that the woman who helped carry out the shooting in San Bernardino, Calif., pledged allegiance to the Islamic State terrorist group and its leader in a social media post.

The post has led investigators to believe the woman, and her husband, were self-radicalized and took inspiration from the group. Which is not hard to believe with the power of , says University at Buffalo communication professor Michael Stefanone.

"People have access to extremist groups that they never had access to before," says Stefanone, who studies the of technology use, including social media. "Social media significantly increases the size for messages created by extremist groups. Social media enables anyone with a voice to broadcast their messages to a global audience, so our access and exposure to these messages is increasing.

"Fifteen years ago one would have had to fly to Saudi Arabia, for example, but today social media creates access at any time."

Not only does social media increase the audience size, but it also amplifies the polarization of , he says.

Because people are communicating anonymously, it becomes easier to take on a more extreme position, he says. Individuals also take on that extreme position more quickly over the Internet, Stefanone says.

"We know that when individuals communicate online, and especially when they are anonymous, their communicative behavior is more aggressive, and their attitudes become more extreme, faster," he says. "Online there are no checks and balances. Everything happens faster online and attitudes escalate and become polarized."