Editing Group dynamics (section)

====Categories====
Categories are characterized by a collection of individuals who are similar in some way.<ref name=":2" /> Categories become groups when their similarities have social implications. For example, when people treat others differently because of certain aspects of their appearance or heritage, for example, this creates groups of different races.<ref name=":2" /> For this reason, categories can appear to be higher in entitativity and essentialism than primary, social, and collective groups. Entitativity is defined by Campbell<ref>{{cite journal|last1=Campbell|first1=D. T.|title=Common fate, similarity, and other indices of the status of aggregates of persons as social entities|journal=Systems Research and Behavioral Science|date=1958|volume= 3 |issue=1|pages=14–25|doi=10.1002/bs.3830030103}}</ref> as the extent to which collections of individuals are perceived to be a group. The degree of entitativity that a group has is influenced by whether a collection of individuals experience the same fate, display similarities, and are close in proximity. If individuals believe that a group is high in entitativity, then they are likely to believe that the group has unchanging characteristics that are essential to the group, known as essentialism.<ref>{{cite journal|last1=Haslam|first1=N|last2=Rothschild |first2=L |last3=Ernst|first3=D|title=Are essentialist beliefs associated with prejudice?|journal=British Journal of Social Psychology|date= 2002|volume=41|issue=1|pages=87–100|doi=10.1348/014466602165072|pmid=11970776}}</ref> Examples of categories are New Yorkers, gamblers, and women.