Perhaps safety helmets should carry a health warning. Wearing them, it appears, encourages dangerous risk-taking. In an extraordinary study, Dr Tim Gamble and Dr Ian Walker, from the University of Bath’s department of psychology, have shown that wearing a helmet is likely to increase sensation-seeking and make people less safe – even in situations where headgear is not required.

The academics believe that their findings, published in the journal Psychological Science, call into question the effectiveness of safety advice, notably about the wearing of helmets for leisure activities such as cycling. But they also suggest that their conclusions help shed light on far wider issues, such as decision-making in conflict zones.

The pair measured the sensation-seeking behaviour and risk-taking of a group of adults aged 17-56 using a computer simulation. The 80 participants believed they were taking part in an eye-tracking experiment, and were divided into two groups and tasked with inflating an on-screen animated balloon. Half wore bicycle helmets and half baseball caps. Both sets of headgear were fitted with eye-tracking devices.

Each inflation of the balloon let participants earn a fictional currency. At any stage participants could “bank” their earnings, but if the balloon burst all earnings would be lost. Over 30 trials, the researchers tested each individual’s desire to keep inflating the balloon and therefore their appetite for risk.

The results were surprising: “Where a helmet, rather than a hat, was used as the mount for a head-mounted eye-tracker, participants scored significantly higher on laboratory measures of both risk-taking and of sensation-seeking,” they state. “This happened despite there being no risk for the helmet to ameliorate and despite it being introduced purely as an eye-tracker.”

Walker admits to having been puzzled by the findings. “The helmet could make zero difference to the outcome, but people wearing one seemed to take more risks in what was essentially a gambling task,” he said. “Replicated in real-life settings, this could mean that people using protective equipment might take risks against which that protective equipment cannot reasonably be expected to help.”

The study feeds into a growing body of work examining how a person’s attitude to risk is influenced. Much of this is centred around contact or extreme sports.

Several studies have looked at so-called “risk compensation”, suggesting that people may drive differently when wearing seatbelts, or make more aggressive American football tackles when wearing helmets. “But in all those cases, the safety device and the activity were directly linked,” added Watson. “This is the first suggestion that a safety device might make people take risks in a totally different domain.”

Gamble was also at pains to suggest the findings did not mean people should stop wearing helmets. “All this is not to say that people shouldn’t wear safety equipment, but rather to say that the whole topic is far more complicated than most people think,” he said. “If feeling protected does make people generally more reckless – which is what these findings imply – then this could affect all sorts of situations, perhaps even how soldiers make strategic decisions when wearing body armour.”