Terrorist attacks often fuel online hate and increase the expression of xenophobic and antiminority messages. Previous research has focused on the impact of terrorist attacks on prejudiced attitudes toward groups linked to the perpetrators as the cause of this increase. We argue that social norms can contain the expression of prejudice after the attacks. We report the results of a combination of a natural and a laboratory-in-the-field (lab-in-the-field) experiment in which we exploit data collected about the occurrence of two consecutive Islamist terrorist attacks in Germany, the Würzburg and Ansbach attacks, in July 2016. The experiment compares the effect of the terrorist attacks in hate speech toward refugees in contexts where a descriptive norm against the use of hate speech is evidently in place to contexts in which the norm is ambiguous because participants observe antiminority comments. Hate toward refugees, but not toward other minority groups, increased as a result of the attacks only in the absence of a strong norm. These results imply that attitudinal changes due to terrorist attacks are more likely to be voiced if norms erode.

恐怖袭击经常加剧在线仇恨，并增加仇外和反少数群体信息的表达。以前的研究集中在恐怖主义袭击对与肇事者有联系的群体的偏见态度的影响上，这是造成这种增加的原因。我们认为，社会规范可以包含攻击后的偏见。我们报告的是自然试验和野外试验（野外试验）相结合的结果，在该试验中，我们利用收集到的有关德国，维尔茨堡和德国的两次连续伊斯兰恐怖袭击事件的数据2016年7月，安斯巴赫遭到袭击。实验比较了在针对使用仇恨言论的描述性规范明显适用的情况下，针对恐怖分子针对难民的仇恨言论中恐怖袭击的影响；由于参与者观察到了反对少数派的言论，该规范模棱两可。袭击的结果是对难民的仇恨增加了，但对其他少数群体的仇恨却增加了，只有在没有严格规范的情况下。这些结果表明，如果规范受到侵蚀，则更可能表达由于恐怖袭击而引起的态度变化。