I have been meaning to write this post for some time, initially instigated by a discussion with friends about motorcycle and bicycle safety and helmets. Bruce's recent blog post about risk intuition made me think I had already waited too long.
Bruce asserts an odd position that he says is based on a professor's theory of mental risk thermostat:
The University College London professor John Adams popularised the metaphor of a mental risk thermostat. We tend to seek some natural level of risk, and if something becomes less risky, we tend to make it more risky. Motorcycle riders who wear helmets drive faster than riders who don't.
Professor Adams actually argues against seat belt legislation based on data. He says the reason that deaths did not dramatically decline after introduction of seat belt laws is because drivers in seat belts feel less vulnerable and therefore take more risks. I would argue against this being a pure relationship on a number of points (increased numbers of vehicles on the road, reduced levels of competency/experience of drivers, more roads with higher speed/power vehicle etc.). More importantly, however, Adams also suggested that more dangerous driving (that he calls a result of wearing seat belts) impacts all those around, including motorcycles. This is not mentioned by Bruce when he takes Adam's theory to say wearing a helmet means a rider will ride faster than without. Time for a more detailed look. I say Bruce is right in some areas but very wrong in others.
Bruce's point is right with concern to performance. When you wear a full face helmet you have less air/pressure on your face and thus can drive faster in more comfort. I would argue this is the same for vehicles with mandated seat belts. They also just so happened to have bigger engines, bigger brakes, better suspension, etc. that made drivers more prone to performance-oriented driving. The seat belt and helmet thus help performance driving marginally, but changes overall have driven (pun intended) more aggressive behavior and seat belts are hardly isolated as a cause. This is compounded by more performance available to less-experienced drivers for less cost. In other words access to performance was made more available. Adams and Bruce do not seem to adequately account for these factors. Thus, although they are correct in general terms of potential for more risk, I do not see where the helmet and seat belt are sufficiently proven as cause of individuals taking those risks.
Bruce is wrong, on the other hand, to say that putting on a helmet will transform everyone's risk threshold to "faster" than without a helmet. This comes from experience as well as data. First, let me point out that the term "faster" is highly misleading. Some riders will not ride at all unless wearing safety gear, and when they ride will not exceed posted limits. What would the "faster" data look like for this population? Are they even counted because without a helmet they would refuse to ride? Bruce admits risk overall is lowered by helmets, but does not segregate the population in any way other than risk domain:
Our risk thermostats aren't perfect (that newly helmeted motorcycle rider will still decrease his overall risk) and will tend to remain within the same domain (he might drive faster, but he won't increase his risk by taking up smoking), but in general, people demonstrate an innate and finely tuned ability to understand and respond to risks.
Let it be said, incidentally, that motorcyclists who do not wear full face helmets are significantly more likely to smoke while riding (can't fit a cigarette in a full face helmet)…but I digress. Frankly, this suggests to me that Bruce does not ride a motorcycle. Why do I say this and why is that important? Because empathy is a huge factor in understanding risk calculations. I will explain more, but first I suspect I say this for the same reason that Fernando Pereira takes issue with comments about skiers wearing helmets. Fernando is a skier and it is from this empathetic view he points out that a feedback loop is necessary for people to modify behavior around risk. If you put on your helmet and feel much safer, due to a lowered risk signal, then you might choose to ride with more risk. Helmets, as well as seat belts, tend not to give any of this feedback. They certainly pale in comparison to a tight suspension and big brakes. Note that he also cites changes in ski technology very similar to what I mention above with vehicles, that have a more profound impact on risk.
In snowsports, other technical improvements affect close call rates, in particular recent skis, which are much more stable and manoeverable at speed, and very powerful snowmobiles that make it easier for riders to manage dangerous snow conditions.
With all that being said, my original post on this subject was going to highlight the rise of data that has shown a disturbing reverse-risk effect of wearing a helmet — there are more threats to your safety when you put one on. Just to be clear, we are talking about risk in terms of threats, vulnerabilities and asset value. In this case the person's health is the asset, a helmet reduces vulnerabilities, but it also might increase threats.
This is where I think Bruce really misses the boat. The risk formulas and data we are exposed to form our threshold for risk, as well as the feedback mentioned above. There are things we can anticipate and those we can not control. How we control our own risk also can be seen in terms of the reaction in those around us. This is essentially the converse of the more libertarian view that we alone control our risk such that if we are forced to use a control (e.g. seat belt or helmet) we all will make ourselves more vulnerable as a response. A report by the BBC, for example, shows perceived gender of a bicyclist will affect the behavior of drivers around her.
While wearing the wig, drivers gave him an average of 14cm more space when passing.
That suggests while helmets may make you less vulnerable, dressing like a woman will also decrease threats, at least in the society that was studied. Don't get excited about wearing a wig just yet. This might not hold true in places like Uganda, as I have mentioned before, where the appearance of women in miniskirts supposedly made it less safe for men to drive.
Back to helmets, how do you behave when studies show you actually are more at risk (due to increased threat levels) when you wear a helmet because of driver reactions around you? What if we knew that putting on the helmet makes us less safe? Will we ride more safely and be less vulnerable with the helmet on, or will we instead remove our helmet and say it is offset by the decrease in threat? Psychologist Dr. Ian Walker did tests on over 2,500 motorists while riding in Bristol and Salisbury and the behavior of drivers when they see a helmet is quite disappointing.
[He] used a bike fitted with a computer and an ultrasonic distance sensor to find drivers were twice as likely to get close to the bicycle, at an average of 8.5cm, when he wore a helmet.
The threat therefore can be altered as vulnerabilities are altered, but not in a manner as predicted or described by Adams. This is not to say all drivers will take more risk when they see a cyclist with a helmet, or that all riders will behave more cautiously when they know that drivers are aiming for helmeted riders. See how intuition falls down (pun not intended)? How can we account for the differences among individuals?
Empathy plays a major factor. Drivers who also cycle will draw upon their feelings beyond intuition when they calculate risk. Whether or not they wear a seat belt, drivers will have their risk calculations impacted by those around them with whom they can relate. That is why the best formula is to reduce threats and reduce vulnerabilities to reduce overall risk.
When people try cycling, they nearly always say it changes the way they treat other road users when they get back in their cars.
On the other hand, drivers without empathy may pass judgment (e.g. a helmeted rider is to be handled as someone experienced enough to take a close call) or they may calculate their own needs are more important, such as a bus making room for oncoming traffic, or give less way due to their experience as professional drivers.
When you ride, ski, etc. you should begin to see threats as the more dominant factor versus vulnerabilities and know this intrinsically. That is why putting on a helmet, and reducing vulnerability, does not necessarily make someone ride faster. If Bruce rode a motorcycle I bet he would not have made his mistake. The more cyclists, motorcyclists, skiers, etc. around you the safer they will all feel because the threats are lessened. In either case it is interesting to note bigger vehicles apparently increase risk the most to riders.
The study also found that large vehicles, such as buses and trucks, passed considerably closer when overtaking cyclists than cars.
The average car passed 1.33 metres (4.4 feet) away from the bicycle, whereas the average truck got 19 centimetres (7.5 inches) closer and the average bus 23 centimetres (9 inches) closer.
However, there was no evidence of 4×4s (SUVs) getting any closer than ordinary cars.
Previously reported research from the project showed that drivers of white vans overtake cyclists an average 10 centimetres (4 inches) closer than car drivers
Again, this begs the question of intuition. What does your intuition tell you about wearing a helmet around big vehicles? Will putting on a helmet make riders chose streets with more big vehicles? I do not think so.
Whew, the data and psychological analysis could go on forever, but fortunately much of the documentation has been collected already by Treehugger. They were nice enough to leave the forest and explain why cyclists should wear helmets in London, but not in Holland. Hint: it has to do with how the environments are regulated, rather than differences in intuition, as I mention above in terms of empathy. Likewise, they cite a study with a completely different perspective to the idea about helmets leading to more risk by the rider.
Cyclists who chose to wear helmets commit fewer traffic violations, have higher socioeconomic status, are more likely to wear high visibility clothing and use lights at night.
Causality and correlation are suspect here, of course, but that is also the problem with Bruce's dependence on Adam's thermostat theory. It's not just intuition that should be measured and relied upon, we also behave in ways that modifies risk-related behavior both for ourselves (feedback loop) and towards others (judgment).
In conclusion, helmets can give riders a reduced risk sensation and thus enable more speed but it is far less of a factor than other risk-affecting technology and beliefs. Those also need to be considered. Helmets for example are a countermeasure for vulnerability and do not address the critical threat factors. The two should not be confused. A risk equation that looks only at vulnerabilities is flawed, as any IT Director being asked to patch Windows OS will explain to everyone in long and gory detail. Just because you are running Windows XP with patches applied does not mean you are going to be more likely to surf casino and porn sites. Furthermore, human calculations of risk are influenced by many things that are group and socially related. It is totally unrealistic to try and measure things as though we live in a vacuum of potentially rational risk agents. While we might like to think about that in theoretical terms, the infrastructure we use and empathy of others are just two examples of how our risk is determined at a much broader scope in reality than alone.
I am reminded of the time Jerry Seinfeld had funny things to say about helmets on skydivers. Great stuff to laugh about. Do skydivers take more risks with helmets? No, and the helmets will not save anyone from impact after a parachute fails to open. What he did not admit (because it probably is not good material for comedy) is that helmets increase the chances of remaining conscious and alert when exiting the aircraft and immediately after landing, both of which involve treatment by others. Helmets lower vulnerability to threats, even as the risk "thermostat" sits unaffected.