Helmet users take more risks!

[ufkacbln]

Risk Anal. 2011 Mar 18. doi: 10.1111/j.1539-6924.2011.01589.x. [Epub ahead of print]
Risk Compensation and Bicycle Helmets.

Phillips RO, Fyhri A, Sagberg F.
Abstract

This study investigated risk compensation by cyclists in response to bicycle helmet wearing by observing changes in cycling behavior, reported experience of risk, and a possible objective measure of experienced risk. The suitability of heart rate variability (HRV) as an objective measure of experienced risk was assessed beforehand by recording
HRV measures in nine participants watching a thriller film. We observed a significant decrease in HRV in line with expected increases in psychological challenge presented by the film. HRV was then used along with cycling pace and self-reported risk in a field experiment in which 35 cyclist volunteers cycled 0.4 km downhill, once with and once without a helmet. Routine helmet users reported higher experienced risk and cycled slower when they did not wear their helmet in the experiment than when they did wear their helmet, although there was no corresponding change in HRV. For cyclists not accustomed to helmets, there were no changes in speed, perceived risk, or any other measures when cycling with versus without a helmet. The findings are consistent with the notion that those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster. They thus give some support to those urging caution in the use of helmet laws.
© 2011 Society for Risk Analysis.

 

[adscrim]

does it mention whether the helmet wearers percieve the risk to be greater than their non helmet wearing counterparts? It makes sense that a helmet wearer would be more cautious without a helmet as they already believe the activity is risky enough to merit a helmet. The question is whether the helmet leads to them taking more risks than non-helmet wearers or simply leads to them catching up in terms of risk taking.

 

[Bman]

Well whatever the case, hopefully they can scientifically win the helmet debate one way or other... for good.

Then we can get down to the important matters. Motor vehicles are killing people.

 

[mangaman]

Risk Anal. 2011 Mar 18. doi: 10.1111/j.1539-6924.2011.01589.x. [Epub ahead of print]
Risk Compensation and Bicycle Helmets.

Phillips RO, Fyhri A, Sagberg F.
Abstract

This study investigated risk compensation by cyclists in response to bicycle helmet wearing by observing changes in cycling behavior, reported experience of risk, and a possible objective measure of experienced risk. The suitability of heart rate variability (HRV) as an objective measure of experienced risk was assessed beforehand by recording
HRV measures in nine participants watching a thriller film. We observed a significant decrease in HRV in line with expected increases in psychological challenge presented by the film. HRV was then used along with cycling pace and self-reported risk in a field experiment in which 35 cyclist volunteers cycled 0.4 km downhill, once with and once without a helmet. Routine helmet users reported higher experienced risk and cycled slower when they did not wear their helmet in the experiment than when they did wear their helmet, although there was no corresponding change in HRV. For cyclists not accustomed to helmets, there were no changes in speed, perceived risk, or any other measures when cycling with versus without a helmet. The findings are consistent with the notion that those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster. They thus give some support to those urging caution in the use of helmet laws.
© 2011 Society for Risk Analysis.

I agree I'm afraid Cunobelin - this study is so small and lacking in staistical data as to be meaningless.

The HRV stuff sounds fancy "science" - there was no difference in the 2 cycling groups - so it was irrelevant.

A few cyclists without helmets rode a bit faster down a gentle hill.

There is nothing about the experience of the cyclists - the non-helmetted may just have been better cyclists?

 

[ThePainInSpain]

Yet another waste of time and money 'study'. To give someone the opportunity to sound superior.

 

[dellzeqq]

the odd thing about this study is that it, in effect, it makes an argument for freedom of choice while suggesting that the choices made by people are not free. Either you trust people to make a choice or you don't - and, if you do, then considerations of how people behave when they make that choice are neither here nor there. 'Science' (if that's a dignified way of saying 'calculation') doesn't matter.

 

[srw]

"Cyclists who are used to wearing helmets rode more catiously when asked to ride without them". Not exactly earth-shattering, and a much fairer presentation of the results of the study.

 

[Danny]

I am also dubious about the fact that cyclists were "self-reporting" the level of risk they took - this is hardly an objective measure.

 

[dellzeqq]

But the study isn't about cycling helmets, it's about risk compensation - which is surely something we need to understand as fully as possible so it can be factored in to all sorts of aspects of life?

Understanding how people behave once they've made their choices, and why they make the choices they do, is pretty fundamental isn't it? Don't you want to know what the factors are that govern, for example, the process your doctor uses to choose a diagnosis for you from the range available to her/him? Reasoning and decision-making is a huge area of study, and probably underlies this study too.

I'm sure you're right about risk compensation, but the nub of it is this - helmets are available to those that want them. Those that do, and those that don't can, as individuals, decide how they ride.

As an academic exercise it might be worthwhile, but as a 'scientific' building block of policy it's neither here nor there. You're either pro-choice or anti-choice, and, I suspect that most of us are pro or anti for reasons that have less to do with risk and more to do with outlook on life.

I don't disbelieve the conclusions, by the way (although I take the point about sample size, and srw make a valid point). Equally I firmly believe that helmets can prevent head injuries. I'm simply not going to wear one.

 

[jonesy]

dellzeqq, I agree with your position on choice, however it really is important to understand risk compensation and other aspects of road user behaviour so that policy making can be better based upon evidence. This isn't particularly about helmets (or the quality of this particular study), but there are plenty of examples of practices that have been adopted because it is assumed they make the roads safer (e.g. barriers, lots of road markings, strictly define priorities etc), but which there is now evidence can make matters worse, by giving people a false sense of safety.

 

[Mad at urage]

"Cyclists who are used to wearing helmets rode more cautiously when asked to ride without them". Not exactly earth-shattering, and a much fairer presentation of the results of the study.

Precisely and:

"For cyclists not accustomed to helmets, there were no changes in speed, perceived risk, or any other measures when cycling with versus without a helmet."

So those who choose not to wear helmets do not 'compensate' by cycling faster when they do wear helmets.

"The findings are consistent with the notion that those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster."

Alternatively they perceive an increased risk when not wearing a helmet and cycle slower. Their normal cycling pace is the pace they cycle at when wearing a helmet. Quite different really!

 

[Wobblers]

Precisely and:

"For cyclists not accustomed to helmets, there were no changes in speed, perceived risk, or any other measures when cycling with versus without a helmet."

So those who choose not to wear helmets do not 'compensate' by cycling faster when they do wear helmets.

"The findings are consistent with the notion that those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster."

Alternatively they perceive an increased risk when not wearing a helmet and cycle slower. Their normal cycling pace is the pace they cycle at when wearing a helmet. Quite different really!

No. It's the same thing. They perceive an increase in risk without the helmet and compensate for it. In other words, this observation supports their conclusions: that cyclists who wear helmets perceive themselves to be at less risk and adapt their behaviour to take more risks.

 

[Wobblers]

I don't think such a tiny sample, composed of volunteers therefore self-selected, each performing once in each of two conditions, really demonstrates anything much. This must be a preliminary study, which would need to be replicated many hundreds of times to show any significant effects.

"Replicated many hundreds of times"?? Most of the medications prescribed have not been tested to that extent. It's not necessary. You need studies of a sufficient size, with rigourous procedures and methodoloy for that. Merely repeating the same experiment again and again - possibly with the same systematic faults and biases - is unhelpful.

As for the size - yes it is small. But that doesn't necessarily make the results statistically meaningless. The figures that are missing from that abstract are the most important ones - the chi squared values or standard deviation (depending on the statistical analysis). Those measure the degree of confidence in the results. A small value means the results are highly significant and not likely to be down to chance while a large value would mean the opposite. Further - and larger - studies are definitely needed, but that doesn't mean this can simply be dismissed. Unless there's contradictory evidence, of course. I'm not aware of any - but I've not looked at the published literature so it's quite possible something does exist.

"Composed of volunteers therefore self-selected". I trust you can prove that assertion?

 

[Wobblers]

Indeed. It's not the risk compensation by cyclists you have to worry about - it's the risk compensation by motorists that's the killer.

Exactly this. To my knowledge, there's only been two studies which compared the behaviour of motorists between helmetted and bare headed cyclists. Both showed the same effect: that motorists pass closer to helmetted cyclists than unhelmetted cyclists. The fact that two different studies, using different methodologies agreed is strong evidence of a real effect here (stronger, in fact, than epidemological studies looking at the benefits of helmets - which show little or no evidence of benefit from helmets).

Motor vehicles are by far the biggest threat we face on the roads. I don't need drivers of one and half tonnes of metal taking more risks with my life, thank you. That is probably the principal reason I've chosen not to wear one.

 

[blubb]

Don't really have experience with risk compensation, since i only use mine in the woods and i never riden there without one.

However on the snowboard i can fully agree. Got one that also covers my ears and it takes all the wind noise away, that way you feel you are driving a lot slower than you would without.