You can't see me

Written by Dee

The science behind "I just didn't see you"

Many of you may have heard this phrase before, you may not remember much before or after but the feeling when you hear that will stir up emotions, but hopefully not trigger a custodial sentence, you definitely won't forget.

"30 motorcyclists are killed or injured every day at junctions"

So why do people look but not see and why does it happen so often. Granted some of the times you just have poor drivers with no awareness but most of the time drivers will look but just not see you.

The human eye

Some of you may know that the human eye works by allowing light to enter through your pupil then your lens focuses the light onto the photoreceptors that make up your retina at the back of your eye. The light is then turned into electric signals that's sent to your brain along the optic nerve to analyse the range of light in an image creating a picture. BUT did you know throughout this whole prices the human eye is never stationary, in fact the human eye is not capable of registering a stationary image. The only reason we see stationary objects such as buildings and parked vehicles is because our eye is constantly making tiny movements making the stationary object jiggle across our retina. If we used sophisticated eye tracking software to stabilise the movement of the eye, we would actually be almost blind, this phenomenon is known as the Troxler effect or Troxler's Fading.

Troxler effect - can you see for yourself?

When your eye is fixated on one point, due to unchanging stimulus away from the fixation point, items in your peripheral vision will start to fade and disappear. The effect is much more enhanced if the object is small and works far more effectively the further away the stimulus is away from the fixation point, like a bike approaching in the distance.

Try it for yourself - Look at the red dot on the right or cross on the left, fixate your gaze at these points and don't blink. In a few seconds the right image will disappear and the dots on the left will disappear.

image sources

Can't see the forest for the trees?

When we couple this information with a phenomena first discovered by fighter pilots it all becomes clear. Fighter pilots noticed when travelling towards each other at high speeds in a straight line, the rate at which the size of the plane would change when further away would be very small, but when it got very close, the rate would suddenly increase dramatically.

As you can see in this illustration, the further away the travelling object the smaller the rate of size change, and at high speeds the sudden "appearance" of the travelling bike is experienced. Until the sudden appearance of the vehicle and due to only small changes in size on it's distant approach the vehicle does not cause any disruption, as far as the eye can see, to the terrain and drivers may not pick up on the movement.

So coupling this phenomena with how the human eye works and the Tuxlor effect, when a motorbike is moving at speed in a straight line approaching a junction, a driver looking in the cyclists direction may experience this blindness.

That being said this doesn't mean that some drivers just have poor road awareness and need reeducation but I would like to think the majority of drivers do stop and genuinely look.

Is there any hope?

Well as bikers we always put ourselves at risk when we hit the roads and all we can do is try to minimise those risks if we want to continue riding. The most important thing when coming to junctions is to ride as if we are invisible and always assume the driver is out to get you. Prepare yourself and anticipate them pulling out and adjust your speed when approaching the junction to allow yourself some time to react.

Most of the new bikes have headlights that turn on automatically, if you are riding an older bike make sure you switch them on even in the day. Sometimes the glare of the light will attract more attention than your inconspicuous 200kg machine and earth trembling exhaust.

Finally, gently adjusting position as you approach a junction will also help attract attention, instead of continuing on a completely linear path, gently adjust your position once or twice as you approach to stimulate the drivers retinas.