旁觀者是影響網路霸凌動態變化的最重要角色，我們期待更多的旁觀者在網路霸凌中可以支持或保護受害者，而不只是做一個冷漠的局外人。因此增加旁觀者在網路霸凌中的積極介入是一個值得關注的議題。先前研究發現網路霸凌情境中的匿名身份會抑制旁觀者介入，然而本研究從社會交換理論角度出發，認為網路匿名身份有助於旁觀者在介入網路霸凌時降低可能付出的幫助成本，例如潛在的負面評價、被報復的風險等，從而保護了旁觀者的介入傾向，所以匿名旁觀者的介入傾向應高於具名旁觀者。然而為何以往研究未能發現這一效果？本研究認為情境幫助成本是一個重要調節變項。可預見的是在情境幫助成本較高時，匿名對幫助成本的降低才會顯得有意義。因此，本研究假設匿名性與情境幫助成本對旁觀者介入的影響存在交互作用：在高幫助成本的網路霸凌情境中，匿名的旁觀者會比具名的旁觀者有更多的介入傾向。在低幫助成本的網路霸凌情境中，依據以往研究的結果，匿名旁觀者的介入傾向會低於具名旁觀者。
在研究一中，151名高中學生被隨機分派至「匿名」或「具名」旁觀者組，並用參與者知覺的「校園排斥」程度作為參與者在校園霸凌情境中幫助成本的指標。參與者們隨後閱讀了一篇有關校園網路霸凌事件的模擬情境，該情境描述了某同班同學在網路論壇中被人揭露了尷尬的秘密並被留言惡語相向。結果支持了匿名性與幫助成本存在顯著的交互作用。條件化效果分析顯示，在知覺校園有較高排斥程度的參與者（較高「幫助成本」，PR > 58）中，匿名組的參與者會比具名組有更高的介入傾向，但對於知覺校園有較低排斥程度的參與者而言（較低「幫助成本」，PR < 58），「匿名」與「具名」組並不存在顯著的組間差異。
研究二增加了對網路霸凌情境中幫助成本的主動操弄，在情境中將提供旁觀者高或低「被報復風險」的線索，並與匿名性（「匿名」或「具名」）形成了2 × 2組間設計。未參與研究一的197名高中學生被隨機分派至四組，並閱讀了與研究一相似的情境。結果發現匿名性與情境幫助成本對旁觀者介入的交互作用仍然顯著：在低情境幫助成本時，匿名組的參與者的旁觀者介入傾向低於具名組，不過組間差異未達顯著（p = .081）；但在高情境幫助成本下，匿名組的參與者的旁觀者介入傾向顯著高於具名組。在情境幫助成本的調節下，匿名性對旁觀者介入的影響效果發生了翻轉。研究二還驗證了一個調節式中介模式以助於揭示內在機制，發現在高情境幫助成本下，「匿名」組相較於「具名」組，所知覺的幫助成本較低，並因此提升了介入傾向，但低情境幫助成本下，並不存在這一間接路徑。

Bystanders are the most important role in influencing the dynamic change of cyberbullying. We hope that more bystanders can support or protect victims in cyberbullying, instead of just being indifferent strangers. Therefore, it’s a real concern that how to increase the positive intervention of bystanders. From the perspective of social exchange theory, this study argued that anonymity online can help bystanders to avoid the adverse consequences of intervention in cyberbullying, such as potential negative evaluation and the risk of retaliation, so as to protect the intervention tendency of bystanders. Obviously, this effect should only be found in the cyberbullying situation where the cost of helping is high. And it may not have a significant effect when the cost of helping is low, even if anonymous identity can avoid such cost of helping. Therefore, this study hypothesized a significant interaction between anonymity and the cost of helping: anonymous bystanders are more likely to intervene than named bystanders in the cyberbullying where the cost of helping is high.
In study 1, 151 high school students were randomly assigned to anonymous or named condition, and the degree of "school exclusion" of participants were used as the indicator of the cost of helping in the following scenario. Then the participants read a simulated cyberbullying scenario, in which someone revealed your classmate’ embarrassing secrets in an online forum and the comments also attacked your classmate. The result supported a significant interaction between anonymity and the cost of helping. Conditional effect analysis showed that anonymous (vs named) participants with a high-cost of helping (PR > 58) had higher bystander intervention. but there was no significant intergroup difference for participants with a low-cost of helping (PR < 58).
In study 2, both anonymity and the situational cost of helping were actively manipulated. 197 high school students who were not involved in study 1 read a similar scenario. The results showed that the interaction between anonymity and situational cost of helping on bystander intervention was still significant: participants in the anonymous condition at low situational cost of helping had lower, but not significant, bystander intervention than participants in the named condition (p =.081). However, participants in the anonymous condition had significantly higher bystander intervention than participants in the named condition when the cost of helping was high. To some extent, the influence of anonymity on bystander intervention is reversed by the moderation of cost of helping. This study 2 also examined a moderated mediation model, and found that under high situational cost of helping, the anonymous condition would perceive a lower cost of helping and affect bystander intervention through perceived cost of helping partly, but in the low help cost situation, there is no such indirect path.

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