Low-probability, high-impact events: Why are people afraid of terrorism?

Low-probability, high-impact events: Why are people afraid of terrorism?

Why are so many people more worried about dying in a terrorist attack than in a car accident or from the consequences of smoking? Two aspects can help explain this phenomenon: the symbolic significance of terrorism and cognitive biases.

In June 2015, one in two US citizens was worried that they or someone in their family would become a victim of terrorism – the highest level since October 2001.

Whilst worldwide more than 140,000 people have died in one of the over 61,000 terrorist attacks since 2000, only 2.6% of these deaths – fewer than 4,000 – occurred in Western countries.

At the same time, more than US$1 trillion was spent on increased homeland security between 2001 and 2011, as calculated in an academic paper by John Mueller and Mark Stewart. They point out:

[T]o be deemed cost-effective, [the increased spending] would have to deter, prevent, foil, or protect against 1,667 otherwise successful Times-Square type attacks per year, or more than four per day.

This raises the question of why many people are so scared of terrorist attacks and willing to devote substantial resources to their prevention when the probability of dying in one is so low.

As a comparison, smoking causes about 480,000 deaths per year in the US – from a purely utilitarian point of view it might be more cost-effective and more lives could be saved if the money spent on increased homeland security was instead spent on educating people not to smoke. Yet this is not what we observe in practice. Why not?

Source: Wikimedia Commons, 2014

Source: Wikimedia Commons, 2014

Terrorism as an attack on Western values

First of all it is important to remember that terrorism is more than just one of many potential causes of death.

It is a highly symbolic attack on Western culture and values. Following the terrorist attacks on multiple locations in Paris on November 13th, the Islamic State called the chosen locations “precisely chosen targets” and symbols of the “capital of prostitution and vice.”

It could therefore be argued that terrorism prevention is not just about preventing the loss of human lives, but mainly about protecting ‘our’ values, society and sense of security. This implies that measures like cost-effectiveness or number of deaths prevented might be irrelevant – if a society considers it worth it to spend 1 trillion US dollars to instil a sense of security in its citizens, or at least to be seen as ‘doing something’, no further justification might be necessary.

However, this only explains why people might be willing to devote substantial resources to the prevention of terrorism, but not why so many people, despite the extremely low probability, are actually worried about becoming a victim of a terrorist attack. This is where cognitive biases come into play.

Availability heuristic and zero-risk bias

Two cognitive biases might be particularly relevant in this context: availability heuristic and zero-risk bias.

Under the availability heuristic many people tend to assess the probability of an event through the ease with which instances can be thought of. The underlying notion is that if an instance is easily retrievable, it must be important.

It is clear how this relates to terrorism: terrorist attacks in Western countries typically receive extensive attention and media coverage and are therefore very salient in many people’s minds.

In addition, some terrorist attacks such as 9/11 can be thought of as typical black swan events – events that are unpredicted and come as a surprise, have a major impact and are only rationalised by hindsight – and are therefore given even more attention and carry particular emotional weight.

The second relevant bias is zero-risk bias, which refers to the tendency to try to completely eliminate one type of risk even when alternative options might lead to a greater reduction in overall risk.

The main principle underlying this bias is the tendency to think in proportions rather than absolute quantities. For example, a 100% decrease in the number of deaths from a particular cause might be preferred to a 1% decrease in the number of deaths from another cause, even when in the first case the absolute number of deaths fell from 1 to 0 and in the second case it fell from 10,000 to 9,900. Applied to terrorism, this implies that there might be a tendency to prefer a complete reduction in the risk of dying in a terrorist attack to a partial reduction in something more likely, such as the risk of dying in a car accident.

Taken together, the two biases and the symbolic significance of terrorism can help explain why so many people tend to overestimate the likelihood of terrorist attacks.

Categories: International, Security

About Author

Larissa Arabelle Brunner

Larissa Brunner currently works for a research consultancy focusing on not-for-profit organisations. She holds a BA in Economics and Management from the University of Oxford and a Double Master’s degree in European and International Relations from Sciences Po, Paris and Fudan University, Shanghai.