Monday, 11 July 2016

Huh? Study finds taboo billboards improve driving performance

By guest blogger Richard Stephens

The 1994 Wonderbra© billboard campaign with its distinctive “Hello Boys!” catchphrase regularly gets a mention as one of most iconic advert series of all time. Its portrayal of super model Eva Herzigova clad only in black lacey pants and gravity-defying bra is said to have sent drivers veering off the roads. However a new study published in the esteemed journal Acta Psychologica suggests that attention grabbing billboard ads may actually have the opposite effect on driving performance.

Michelle Chan and colleagues from the University of Alberta, Canada, were sufficiently concerned about the effects of driver inattention on road vehicle accident rates that they ran a study using a driving simulator in a bid to find out just what kinds of effects roadside advertising strategies might be having on drivers.

A number of psychology students took a simulated drive along a road that was largely indistinctive apart from a succession of advertising billboards. The hoardings that they drove past each depicted a single word. Some words were deliberately positive (e.g. “liberty”) while others were negative (e.g. “gloom”) and still others were chosen for their neutrality (e.g. “errand”).

Image of driving simulator taken from Chan et al 2016
Eye-catchingly, a further selection of words including “asshole”, “fuck” and “dildo” were chosen because they were taboo. As the students drove along the simulated route a computer measured and recorded how safely they were driving including their speed, lane maintenance (keeping towards the centre of the lane as opposed to drifting left or right), and use of the steering wheel.

Interestingly, on the route passing by the taboo billboards, driving performance did not worsen by any of the measures used. In fact, surprisingly, lane position actually improved. Drivers positioned the car more centrally in scenarios where the billboards at the side of the road contained taboo words like “dildo”. Not only that, but in a spot memory test after the driving tasks had been completed, the volunteers could recall more of the taboo words featured on the billboards compared with the words from the other categories. There were no effects of the other word types other than a small increase in speed (around 2 km/h) when passing by the positive words.

The improved recall of the taboo items echoes previous research showing that swear words are more memorable because they are emotionally arousing. In fact, this emotionally arousing property of taboo words seems to underlie the beneficial effects on driving performance shown in the study. The researchers suggest that the excitement aroused when we encounter a taboo stimulus – like a swear word – can trigger a response known as “cognitive tunnelling”. Effectively, this is a narrowing of the focus of attention to just one part of the visual environment.  Paradoxically this could benefit driving if attention becomes narrowly focused on just the road ahead.

Another way that taboo words on billboards could have improved car control is related to the idea of a rabbit becoming frozen in the headlights of an onrushing car. The paper cites previous research finding that viewing taboo and threatening images can bring about a suppression of the motor system. The authors suggest that any reduction in responsiveness of the musculature caused in this way might improve performance by reducing incorrect responding. However, this seems less likely to me as I would expect any suppression of mobility to impair driving rather than enhance it.

An obvious criticism of this research is that it involved naughty words, rather than risqué images, which is the issue more relevant to real life. However, the researchers point out that regions of the brain involved in processing emotion (for example the amygdala, the prefrontal cortex and the anterior temporal cortex) have been shown to become more activated in response to emotionally arousing pictures compared with emotionally arousing words, and on this basis they actually suggest that scantily clad and attractive models on billboards may well show more pronounced beneficial effects on driving because of a still-greater narrowing of drivers’ attention.

However, while this idea may hold theoretically, any benefits of cognitive tunnelling must depend on drivers quickly returning their attention back on to the road after it has been grabbed involuntarily by a provocative billboard. I predict this would be far more challenging for taboo imagery compared with taboo words. For example, a recent study found that cards players made less advantageous decisions when the backs of the cards depicted sexually explicit images as opposed to traditional card patterns.

Large amounts of planning and money are expended by companies including the makers of the Wonderbra© to make adverts as eye-catching as possible. While this study suggests these ads may unintentionally be contributing to road safety, a great deal more research is needed before anyone might recommend that transport authorities should actively encourage risqué advertising billboards on the roadside.


Chan M, Madan CR, & Singhal A (2016). The effects of taboo-related distraction on driving performance. Acta psychologica, 168, 20-6 PMID: 27136396

Post written by Richard Stephens for the BPS Research Digest. You can read more of Richard’s work in his critically acclaimed popular science book, Black Sheep The Hidden Benefits of Being Bad, available from all good book stores and online. Richard is a Senior Lecturer in Psychology at Keele University and Chair of the Psychobiology Section of the British Psychological Society.

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