"Intergroup dynamics" (or intergroup relations) refers to the behavioural and psychological relationship between two or more groups. This includes perceptions, attitudes, opinions, and behaviours towards one's own group, as well as those towards another group. In some cases, intergroup dynamics is prosocial, positive, and beneficial (for example, when multiple research teams work together to accomplish a task or goal). In other cases, intergroup dynamics can create conflict. For example, Fischer &amp; Ferlie found initially positive dynamics between a clinical institution and its external authorities dramatically changed to a 'hot' and intractable conflict when authorities interfered with its embedded clinical model. Similarly, underlying the 1999 Columbine High School shooting in Littleton, Colorado, United States, intergroup dynamics played a significant role in Eric Harris’ and Dylan Klebold’s decision to kill a teacher and 14 students (including themselves).