• The more certain the knowledge about the agent of attack, the more likely it is that outrage and a call for retaliation will stand out from other behavioral and emotional reactions.

• The more the attack is seen as inhumane, the more likely it is that the public will feel sadness, depression, and rage.

• The greater the clarity of information communicated about the nature of the attack—along all of the dimensions above—the weaker will be any fear and terror reactions.

• The better the fit between that information and the previously established preparedness procedures and routines, the less likely there will be extreme emotional responses and disorganized behavior and the more orderly the withdrawal, help-seeking, rescue, and other coping behaviors.

• The greater the degree to which the target is symbolically laden (e.g., sacred), the greater the shock and anger in relation to other emotional responses.

All these principles apply to the social-psychological perceptions of an attack that result from the adequacy or inadequacy of knowledge about the situation. These perceptions derive from interpersonal communication of information, the spread of rumors, and above all the immediate reporting and interpretations of the event by the mass media.

The media play an important role in defining the nature, scope, and level of threat in critical situations, in disseminating both reliable and unreliable information, and in calming the population or generating extreme reactions such as anxiety and terror. This truth has become even more evident as technology now permits instant worldwide dissemination of news and opinion. A special responsibility for reporting and dissemination seems to attach to events that are immediate, threatening, and easily generalizable.

The role of the media is double-edged. On the one hand they can displace informal and uncontrolled flows of information with accurate, timely, and authoritative reporting. On the other hand they can be conduits—and multipliers—of misinformation if they report soft “facts” and unconfirmed rumors, often in the rush of trying to scoop competitors. Indeed, the media can inadvertently change the basic dimensions of an attack. The widespread reporting of the anthrax contamination in the weeks after September 11 served to expand those events from several localized incidents into a potential generalized threat. All this underscores the crucial roles of both the mass media and authoritative sources such as the police and political leaders in giving definition (psychological reality) to an attack. It also underscores the great need for responsibility and prudence on the part of these entities in moments of crisis.