School shootings across the country continue to discuss the story of the student who is outcast by fellow peers and decides to lash out. These reports may leave some wondering if ostracism is a legitimate cause for violence. Kip Williams believes it is. Williams, a professor of psychology at Purdue University, recently came to campus to speak about the effects of being ostracized. These effects can be distressing, but they often go unnoticed, he said. 'I would have rather been beaten or bullied than be ignored,' Williams said, reflecting on what some of the participants in his experiments felt after they were left out of a game of toss. 'Even two minutes of invisibility is painful,' he said. Ostracism, the act of ignoring or excluding, is a phenomenon not only found in the adult world, according to Williams. Children play simple games which leave peers out without being taught to do so. Even animals use forms of ostracism, Williams said. Lions, wolves and bees, for example, use the tactic to keep out burdensome members of their groups, which often results in death for the excluded member. Exclusion among humans can be similarly detrimental, he said. Williams conducted a computer game of toss, and showed the results for those who did not receive the ball. Their angry, disappointed and saddened faces showed just how important inclusion is in human interaction. In another experiment, the excluded participants had no control over loud noises entering their headphones. The result was that they chose to act out against fellow participants. That lack of control is what Williams believes triggers aggression. 'When control is robbed, then people don't care about how they are being liked anymore,' Williams said. 'They just want to establish control by being recognized. People are more likely to be violent in order to get that recognition,' Williams said. His research has found that people are generally ostracized at least once a day, like the waiter who refills water glasses without notice, or the person who sits next to you on the bus without a glance. These interactions may not seem like much, but Williams asserts that even the slightest situations in which people feel invisible can have a negative impact on them. In his studies, a total of 70 percent of people said they had been given the 'silent treatment' by their loved ones. The central concept of the passage 'ostracism' most probably refers to ______.