Drivers using hands-free phones can become just as distracted as those using handsets, a study suggests. But even when drivers aren't on the phone there are plenty of things that can ruin their concentration.

Spiders

It's horrible when you feel eight little legs creeping up your arm. Even drivers without a phobia of spiders can become distracted and agitated. Just a glimpse of one scuttling across the dashboard can be enough.

In 2010, a motorist in Devon who threw a spider out of her car window crashed into a man on a charity bike ride. There was another case last year, when a car crashed into a lamp post in Poole, Dorset, after the driver became distracted by a spider.

"You need to stop the car and deal with the issue," says Neil Greig, policy and research director at the Institute of Advanced Motorists. "Continuing to drive with that kind of distraction is a bad idea."

Greig says opening the window might help to get rid of the spider, but this still diverts the driver's attention from the road.

The Department for Transport doesn't list separate figures for road accidents prompted by arachnids, but overall in 2014 police in Britain said distractions of all kinds inside vehicles had been listed as a cause of 68 deaths and 445 serious accidents.

Mobile phones, by contrast, were cited as a cause of 21 deaths and 84 serious accidents.

Emotional turmoil

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Motorways are dotted with signs warning drivers to take a break. "Tiredness kills," they're told. But their emotional state can be important too.

Researchers at Virginia Tech suggest that drivers increase the risk of a crash nearly tenfold when they get behind the wheel "while observably angry, sad, crying, or emotionally agitated".

The effect can be as detrimental to road skills as daydreaming, says psychologist Sandi Mann, author of The Upside of Downtime: Why Boredom is Good. "The problem is that you don't want anything that distracts from the task," she says.

Mann recommends tailoring the music played in the car to ensure there isn't a "cognitive overload" resulting from songs with too much personal emotional meaning. "You need some upbeat music, just enough to help you concentrate," she adds. CDs designed specifically for use by drivers and truckers work well, Mann says, as do songs by Queen.

Grooming

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It's not uncommon to see motorists applying make-up or brushing their hair while stuck in traffic, but to do so while the vehicle is moving is clearly a bad idea. Some men have been caught shaving while driving - presumably without the use of foam and hot towels.

In the US, self-grooming behind the wheel is a big enough problem for the road-safety group Decide to Drive to issue advice on how to avoid it.

The group recommends getting ready before leaving the house... failing that, it advises drivers to keep items like tweezers, brushes and lipstick off the passenger seat to keep temptation at bay.

In the UK, there's no specific offence of self-grooming while in control of a motorised vehicle, but it is covered by laws against careless driving.

The scope of the problem is unknown, but Greig says it goes on in the UK and recommends - as when a spider is present - pulling over before taking action.

Eye candy

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A recent survey in Australia suggested that 59.2% of male drivers were distracted by "good-looking women". Women were less easily swayed, 15.2% reporting the same reaction to attractive men.

It's not just Australians who are affected, says Greig. "It's definitely an issue, particularly in the summer." In 1994, a billboard advertisement showing the model Eva Herzigova wearing just a bra, and bearing the message "Hello, boys", was blamed for causing accidents and slowing down people's commute to work.

Greig doesn't offer a specific solution to this form of distraction, but encourages people to "take their driving seriously", blanking out imagined pleasures of the flesh whenever possible.

What the Australian survey does highlight is that it's not just what happens inside a vehicle that puts drivers off. The Department for Transport says in 2014 police reported 19 deaths and 206 serious accidents in which a distraction outside the vehicle was listed as a cause.

Adults

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There's nothing more annoying than trying to drive when kids are shouting and fighting in the back, right? Well, actually there is, the Royal Society for the Prevention of Accidents suggests - adults.

Over-18s are listed as a distraction by 22.9% of drivers, it says, basing this on research carried out in the US. Only 12.9% said the same of children.

Could one reason for this be that parents are so used to a racket from their kids that it becomes little more than background noise? "It might be that arguments with adults are a little more emotionally involved," says Greig.

Mann says chatting between adults can actually stimulate the driver, as it prevents weariness, but recommends not overdoing it.

And if an unavoidable row is brewing, the same advice applies as for dealing with spiders and the urge to self-groom: pull over first.

Follow Justin Parkinson on Twitter @justparkinson

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