If you can't join them, beat them: Effects of social exclusion on aggressive behavior.

Social exclusion was manipulated by telling people that they would end up alone later in life or that other participants had rejected them. These manipulations caused participants to behave more aggressively. Excluded people issued a more negative job evaluation against someone who insulted them (Experiments 1 and 2). Excluded people also blasted a target with higher levels of aversive noise both when the target had insulted them (Experiment 4) and when the target was a neutral person and no interaction had occurred (Experiment 5). However, excluded people were not more aggressive toward someone who issued praise (Experiment 3). These responses were specific to social exclusion (as opposed to other misfortunes) and were not mediated by emotion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)