Threating of intergroup differentiation is effective factor in bias and attitude to outgroup, affective state and collective self-esteem

This study aimed to examine the effect of intergroup similarity in bias, identification, attitude, affective state and collective self-esteem. 84 Math students using of tow design of post-test with control group and repeated measure were selected via available sampling and randomly were assigned to experimental and control groups. Then in tow condition high similarity and low similarity completed the collective selfesteem questionary and answered to questions about attitude, bias, identification and affective state that were resulted from pervious research. results from tow experimental condition high similarity and low similarity showed significant differences in collective self-esteem (t=2.17, p<0.05), bias (t=3.47, p<0.01), negative attitude (t=-4.8, p<0.0001) and affective state (t=2.24, p<0.05) but manipulating similarity dosnt have significant affect in identification with ingroup (t=- 1.77, p>0.05). this results show that increasing intergroup similarity not only redound reducing collective self-esteem, makes bias and negative attitude to outgroup and experience of negative affect.