Do anti-lock brakes or bike helmets *increase* risk, since people adapt to the measure and therefore corner faster or use less self-protective behaviours?
A lot has been said about Risk Homeostasis (RH), Risk Compensation (RC) or the Peltzman effect.
But as it seems, we have little convincing, rigorous evidence that its core premises are demonstrable – e.g. safety measures are offset by adaptive behaviours in order for people to maintain an internal homeostatic appetite of ‘risk’.
Attached is a 2016 article discussing some challenges to the concept (shared here under an open access licence).
Despite quite a bit of evidence to the contrary, these ideas persist. For Pless, at least, “this is a dead horse that no longer needs to be beaten”. A key finding is the scarcity of RCTs supporting the concept.
Another article from Thompson et al. (2001, Injury Prevention) remarks that, specifically for helmet use:
“The scientific evidence … indicates that bicycle helmets protect against head, brain, severe brain and facial … injuries has been well established”, AND “We believe that the evidence indicates such a strong protective effective of helmets, that the net effect on the health of the public will be positive”.
Similar null effects were found with COVID masks, and a myriad of other areas. An earlier 2000 systematic review concluded similarly, that while there was, at that time, a few limited interesting studies suggesting a compensatory effect – overall it was weak and not particularly convincing.
For Thompson et al., the burden of evidence lies with the proponents of RH/RC.
Interestingly, some newer work is concerned about the effectiveness of STI treatments, and how they may amplify hazardous sexual behaviour.
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NB1. These articles don’t rule-out the effects of behavioural adaptation and/or compensatory markers, which has been shown in some studies; but they challenge the claim that people reliably adjust their behaviours to some internal target risks, and that safety benefits are offset.
NB2. Some argue that RH and RCT are different, and that RCT may have marginally more convincing evidence than Wilde’s RH.
SafetyInsights.org 