本研究從印象管理理論與傳播隱私管理理論的概念切入，探討社群網站使用 者如何因應社群網站蓬勃發展下導致的情境崩解情境，並提出「分群行為」之概 念。本研究以朋友親密度、關係強度以及自我揭露程度作為分群行為之指標，測 量不同社群網站之使用行為，並以臉書和Instagram為探討之社群網站類型。結 果發現，使用的社群網站數量愈多，不同社群網站間的朋友重複程度愈低，意即 使用一個以上的社群網站之使用者確實有分群行為，且臉書和 Instagram 的朋友 親密度、關係強度與自我揭露程度皆有顯著差異。再者，隱私顧慮不會影響分群 行為，但會影響隱私管理行為。自我監控之人格特質對分群行為則有部分影響。

本研究賦予劇場理論新的意義，即前台與後台的分野為不同社群網站，而非線上與線下之別，並以微觀和巨觀的方式探討社群網站使用者的隱私顧慮與自我 監控人格對分群行為和隱私管理行為之影響。

With the flourishing development of social network sites (SNSs), this study discusses how the users of SNSs cope with the situation of context collapse from the views of Impression management theory and Communication Privacy Management theory. This study puts forward the concept of “grouping”, and uses friendship intimacy, relationship strength, and self-disclosure as its indexes to measure the behavior in different SNSs. Furthermore, Facebook and Instagram are the two main types of SNSs being discussed in this study.

Results show that the more numbers of SNSs one uses, the less one’s friends in different SNSs will repeat, which means when one uses more than a social network site, grouping behavior does exist. Besides, there are statistically significant difference in the friendship intimacy, relationship strength, and self-disclosure between Facebook and Instagram. Moreover, privacy concern does not affect grouping behavior, but it affects the behavior of privacy management. Last but not least, self-monitor personality has partly influence on grouping behavior.