Source: http://phys.org/news/2014-04-impact-face...

The studies, published earlier this year, show that the most likely person to be unfriended is a high school acquaintance.

"The most common reason for unfriending someone from high school is that the person posted polarizing comments often about religion or politics," said Christopher Sibona, a doctoral student in the Computer Science and Information Systems program at the CU Denver Business School. "The other big reason for unfriending was frequent, uninteresting posts."

Sibona's first study examined `context collapse and unfriending behaviors' on Facebook and his second looked at `the emotional response to being unfriended.'

Both studies were based on a survey of 1,077 people conducted on Twitter.

The first study found that the top five kinds of people respondents unfriended were:

1. High School friends
2. Other
3. Friend of a friend
4. Work friends
5. Common interest friend

"We found that people often unfriend co-workers for their actions in the real world rather than anything they post on Facebook," Sibona said.

One reason he believes high school friends are top targets for unfriending is that their political and religious beliefs may not have been as strong when they were younger. And if those beliefs have grown more strident over time, it becomes easier to offend others.