Monday, 12 November 2012

... Mind the antelope

Whatever kind of trailer you’re towing, Safe T Signs mean Safe TowingBe seen and be safe when you emerge from junctions or roundabouts, and when you are towing in the dark.

Buy Safe T Signs from our website here:

I read a really interesting blog last week, “What an RAF pilot can teach us about being safe on the road”.

It's aimed at cyclists, but a very stimulating read, and it applies to road safety in general.

“Sorry mate, I didn’t see you” – the hypothesis

John Sullivan is a Royal Air Force pilot with over 4,000 flight hours in his career and a crash investigator.  He's also a keen cyclist.

His key point is:

Our eyes aren't designed for driving.  Our eyes and brain are perfectly designed for creeping up on unsuspecting antelopes and spotting the odd sabre-toothed tiger. But no one primed them for traffic, cars, cyclists,  and I'd argue, trailers and things being towed.


Only a small part of the retina, the centre bit, generates a high-resolution image. This is why we need to look directly at something to see the detail.  The rest of the retina lacks detail but contributes by adding the peripheral vision.  However,only 20 degrees away from your sight line your visual acuity is about 1/10th of what it is at the centre.

Try this test to see quite how much detail you lose in your peripheral vision
  • Stand 10 metres away from the front or back of a car
  • Move your eyes and look just one car’s width to the right or left of that car
  • Without moving where your eyes are now looking, try and read the number plate of the car
  • Try the test again from 5m

This shows you how little detail you see from the side of your eyes.

It's not that we can’t see things in our peripheral vision, but to have a good chance of seeing an object on a collision course, we need to move our eyes, and probably head, to bring the object into the centre of our vision – so that we can use our high-resolution vision to resolve the detail.

Here’s when things get really interesting

When you move your head and eyes to scan a scene, your eyes are incapable of moving smoothly across it and seeing everything. Instead, you see in the image in a series of very quick jumps (called saccades) with very short pauses (called fixations). It's only during the pauses that an image is processed.

Your brain fills in the gaps by combining murky peripheral vision with assumptions that what’s in the gaps is the same as what is seen during the pauses.

Your brain actually blocks the image being received while your eyes are moving. This is why you don't see the sort of blurred image, which you see when you look sideways out of a train window.  The exception is if you’re tracking a moving object.

Another test to try

  • Look in a mirror.

  • Look repeatedly from your right eye to your left eye.

  • Can you see your eyes moving? You can’t.

  • Repeat the test with a friend and watch them. You'll see their eyes moving quite markedly

You can’t see your own eyes move because your brain shuts down the image for the instant that your eyes are moving. This is called Saccadic masking.

In the past, it meant we could creep up on antelopes without our brain being overloaded by unnecessary detail and a lot of useless, blurred images.

However, in a modern day situation, such as a traffic junction, it means we miss "obvious" things?

At a traffic junction all but the worst of drivers will look in both directions to check for oncoming traffic. However, our eyes sometimes “jump over” oncoming bicycles or motorbikes, or trailers behind vehicles.

This isn’t really a case of a careless driver, it’s more of a human incapacity to see anything during a saccade. Hence the reason for so many “Sorry mate, I didn’t see you” excuses..

The faster you move your head, the larger the jumps and the shorter the pauses. Therefore, you’ve got more of a chance of missing a vehicle.

We're effectively seeing through solid objects, with our brain filling in the image.

How accidents happen

So, when you're towing, if other drivers don’t expect there to be a trailer, even a great big one, their brain is more likely to automatically jump to the conclusion that the vehicle they see is the car, and that's all there is to see.

One comment from a tower about people not seeing the obvious includes:

" ....on a large island I was negotiating with my discovery and twin axle tourer when some idiot had not realised I was towing a nearly 8m long caravan and tried to slot in behind my car and then realised his mistake to which I had had to take exceptional driving manoeuvres to avoid a collision!"

Forewarned is forearmed, so here’s what we can do.

Cyclists are very vulnerable and the comments on the London cyclist blog show real understanding and appreciation of the issues.  This includes cyclists relating incidents that happened to them as car drivers, when they haven't been expecting to see something and so on.    I think it's really important that we recognise the special vulnerabilities of cyclists and motor cyclists and support initiatives that will make them safer for them.

Equally, we need to recognise that towing also presents some challenges - if another driver can't see the trailer because of other vehicles, or because it's out of their line of sight, then they will behave like it's not there.

Using a Safe T-Sign on the side of your car means that if other drivers can see your car then they can be alerted to the fact that there's something else to follow your vehicle.  They are reflective, so they will catch the light and the eye of other drivers.  As Safe T-Signs become a more familiar sight on the road, other road users will instantly recognise what they mean and they will register that there is something else to look out for.

I'd be really interested to hear about instance when drivers who tow have found that their trailer, however big or small, is invisible to other road users and whether this it was the antelope effect.

See our website:

Whatever kind of trailer you’re towing, Safe T Signs mean Safe TowingBe seen and be safe when you emerge from junctions or roundabouts, and when you are towing in the dark.

Buy Safe T Signs from our website here:

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