It’s well-known that people have trouble measuring risk.
A study from 1978, ‘Judged Frequency of Lethal Events‘, showed that, when estimating the relative probability of various dangerous events (homicide or suicide, accident or disease), subjects used the availability heuristic. The more readily an event could be brought to mind – due to vividness or media coverage – the more likely it was considered to be.
So the incidence of spectacular disasters (plane crashes, terrorist attacks) is overestimated, while less dramatic but more common causes of death are underestimated.
For some reason, the former (overestimation) variety of error gets most of the attention.
Over the past few years people like Frank Furedi have started banging on about a ‘culture of fear‘, of successive panics aroused over global warming, BSE, Y2K bug, terrorism, SARS, avian flu, etc. Furedi, it’s true, is a crank, but more worthwhile studies have also shown how hysterical media reporting induces availability bias by exaggerating new health threats.
Meanwhile Gerd Gigerenzer famously showed that excess US road accident fatalities (353) in the last 3 months of 2001, probably due to people avoiding air travel, outnumbered the 266 passengers and crew killed while flying on 11 September. Despite the hyping of terrorism’s threat by governments and media, the lifetime chance of death from a terrorist attack is roughly equal to the risk of dying from another low-probability, high-consequence event like an asteroid strike.
Clearly, given the tendency of risk perception to outrun objective probability, reality checks are necessary.
Unfortunately, somewhere along the line contrarian warnings against ‘alarmism’ have acquired a kind of prestige, and it’s become a marker of high status to suggest that nothing bad can ever happen. H1N1? Scaremongering by the media and WHO, both in the pay of big pharma. Global warming? Overblown.
Somebody who wrote a book called The Existential Jesus can, with a straight face, intone against ‘causes that attract pseudo-religious enthusiasm and intellectual fanaticism‘, supported by ‘prophets of doom and the language of apocalypse’.
For such ‘sceptics’, political ideology is often at work, along with a desire to signal their stiff upper lip and intellectual supremacy: I won’t be duped by Al Gore’s mind control! Can’t scare me!
But these examples also show the other side of availability bias: underestimating the frequency of the non-salient.
Almost nobody can remember a high-mortality flu pandemic that disproportionately killed young adults, so we consider it impossible; none of us has ever actually observed human climate forcing, so we dismiss it. These are not even what Nassim Taleb calls ‘Black Swans‘: they are merely beyond our immediate experience, and that’s enough to reduce our risk perception.
One strange example of this tendency is a backlash against ‘peanut allergy hysteria.’
Over the past few decades, the incidence of diagnosed peanut allergies in Australia, the US and the UK appears to have increased sharply. Allergic diseases generally seem to have become much more prevalent since the Second World War. But nut allergies get a lot of attention due to anaphylaxis and a few schoolkid deaths.
It seems likely that parents exaggerate the risk of peanut-related deaths due to the availability heuristic. Some schools have responded with extreme allergen-avoidance measures, like banning nuts completely.
This has led Slate to wonder ‘Are nut allergies taking over the planet?‘ and the New York Times to consider ‘Are Nut Bans Promoting Hysteria?‘ The point is arguable, though much of it is delivered in a silly our-way-of-life-is-non-negotiable style. (‘Taking precautions for the radically sensitive, however, means asking a lot of people to change their behavior.’)
Yet behind the opposition to ‘peanut hysteria‘ seems to be an intuitive refusal to believe that incidence of food allergies or anaphylaxis could be rising. Joel Stein of the Los Angeles Times writes in ‘Nut Allergies – A Yuppie Invention‘ that ‘[your] kid doesn’t have an allergy to nuts. Your kid has a parent who needs to feel special… But unless you’re a character on Heroes, genes don’t mutate fast enough to have caused an 18% increase in childhood food allergies between 1997 and 2007… [It] is strange how peanut allergies are only an issue in rich, lefty communities.’
Nobody seems to doubt the rising prevalence of asthma (asthma rates in Australia doubled between 1982 and 1992) or eczema, conditions which are related to food allergies. Perhaps the difference in attitudes can be explained by the higher population frequency of asthma and eczema, which leave more people with a personal experience (a friend, relative or themselves) of these conditions, and less reason to doubt their legitimacy.
In contrast, I suspect most people find food-induced anaphylactic shock not vivid but unimaginable. Where asthma has through familiarity become domesticated and somewhat mundane, death by peanut seems something that could only be dreamed up by hysterical, overprotective middle-class parents.