Public perception of likelihood of and response to a terrorist attack: Assessing the effects of the Homeland Security Advisory System

Following the terrorist attacks of September 11, 2001, President Bush issued Homeland Security Presidential Directive-3 to establish the Homeland Security Advisory System (HSAS). The resultant color-coded system distinguishes between five Threat Conditions ranging from Low (green) to Severe (red) risk of terrorist attack. This research uses an autoregressive time series analysis from January 2005 to June 2007 to examine the relationship between various HSAS Threat Conditions and the general public's perceived likelihood of a terrorist attack. The influence of media coverage of possible terror attacks and the occurrence of an actual bombing in London on perception of the likelihood of terrorist attacks are studied. Threat Condition did not predict people's perceptions of the likelihood of a terrorist attack. In contrast, people who heard more about possible terror attacks from the media also perceived greater likelihood of an attack. Likewise, following the London subway bombing that occurred in July 2005, the perception of the likelihood of a terrorist attack was significantly higher than the trend. This study suggests that people do not rely on the HSAS Threat Conditions to make judgments about the risk of a terror attack. Instead, both media coverage of terror attacks and the occurrence of an actual terror attack influence people's perceptions of the likelihood of another attack. Implications for government and media policy are discussed.