Five types of people you're likely tounfriend on Facebook.

The most likely person to be unfriended on Facebook is a high school acquaintance, a new study has found. Scientists have found new insight into the most common kind of 'friend' who is unfriended on Facebook, as well as the unfriended person's emotional response to such a situation. Researchers from the University of Colorado Denver found that the top five kinds of people respondents unfriended were: High School friends, other, friend of a friend, work friends and common interest friend. "The most common reason for unfriending someone from high school is that the person posted polarising comments often about religion or politics," said Christopher Sibona, a doctoral student in the Computer Science and Information Systems programme at the CU Denver Business School. "The other big reason for unfriending was frequent, uninteresting posts," said Sibona. Sibona's first study examined 'context collapse and unfriending behaviours' 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. "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. "Your high school friends may not know your current political or religious beliefs and you may be quite vocal about them," Sibona said. "And one thing about social media is that online disagreements escalate much more quickly," Sibona said. The second study looked at the emotional impact of being unfriended. Sibona found a range of emotions connected to unfriending, from being bothered to being amused. The most common responses to being unfriended were: 'I was surprised', 'It bothered me', 'I was amused' and 'I felt sad'. "The strongest predictor is how close you were at the peak of your friendship when the unfriending happened," said Sibona.