How to avoid a collision

SMIDSY collision high visibility road safety

Ever wondered why people drive right out in front of you and cause a collision?
 They call it “SMIDSY” or “sorry, mate, I didn’t see you” syndrome.

It seems surprising, especially when you are riding a big, bright-orange Harley-Davidson Street Glide like I was when a woman in a white Corolla drove straight out in front of me.

But now a Texas Tech University psychologist reckons she has found out why this happens.

I’ll skip all the tech talk and cut to the chase: People think smaller objects are further away than they appear and conversely bigger objects are closer.

SMIDSY crash
SMIDSY crash

Researcher Pat DeLucia used computer simulation to study participants who viewed two approaching objects simultaneously – one large and one small. The viewer had to nominate which would reach them first.

Her study, “Current Directions in Psychological Science”, indicates that an object’s size affects distance perception, causing drivers to miscalculate riders’ distance and speed.

“People generally picked that simpler heuristic: Larger is closer,” says DeLucia.

Unfortunately, motorcycles are the smallest vehicles on the roads, yet are usually the fastest accelerating.

So drivers think we are going to arrive much later than we actually do.

It’s a lethal combination that could be the cause of up to three out of every four motorcycle accidents.

Ok, so what do we do about it?

  • Having headlights on may make you more visible in some circumstances, but it doesn’t make a difference to the size of your bike.
  • Position on the road is important. You need to ride in the wheel track closer to the centre line as this means you are visible sooner to oncoming traffic or vehicles turning across your path. It also gives you a buffer from vehicles suddenly emerging from a roadside parking bay.
  • Weaving from one wheel track to the other also draws attention. It may look erratic and as though you have lost control, but it attracts much-needed attention.
  • Never assume a driver has seen you.
  • Slow down and get ready to take evasive action if you see a vehicle at an intersection.
  • Wait until you see the whites of their eyes before accelerating. And even then, prepare for them to make a sudden move.
  • If so, it is best to think about changing course behind the car, rather than in front of it. The normal reaction is to weave away from the direction that the threat is coming. However, that leads you into the direction the threat is heading, so you may still collide.
  • If you don’t see the whites of their eyes, then it might be time to give a polite toot on the horn to alert them.

So what happened when the Corolla drove out in front of me?

Harley-Davidson Street Glide - New Zealand -
MBW On a Harley Street Glide

I hadn’t followed any of my own advice and was surprised when I saw the car start to move off.

In panic, I hit the brakes and activated the Harley’s excellent ABS front and rear, yet I was still able to steer the bike and turn the corner from where the woman was coming. At least I got that part right.

That’s how good ABS is. On a non-ABS bike, the front wheel would have locked and tucked, and the bike and I would have slid straight into the car. The fact that I could panic-stop and steer at the same time saved my bacon.

I didn’t have the time or awareness to blow the horn and I’m not even sure the driver was aware of the drama they had just caused as she merrily continued on her way.


  1. When I do drive my car, a three year old Lancer I am really aware of riders being one myself but I do think the newer style side mirrors on cars play a big role as the project those behind as being much further away and until you glance in the rear vision mirror you could pull out in front of a bike, or car thinking they are much further behind. I hate the side mirrors on my car and feel on dual carriageways they are downright dangerous.

  2. What happens is called “motion camouflage” – in certain positions on the road as you approach a potential SMIDSY the bike will appear to be motionless and blend in with the background. Even worse – by riding in one wheeltrack or the other your headlight can appear to be part of a car behind you. By weaving you distinguish yourself from the background clutter rather than blending in.

    The research you mention seems to cover the looming effect – objects at a distance appear to remain the same size – when they are quite close they suddenly increase in size rapidly. Another way this can hurt is if the fight-or-flight insinct kicks in – resulting in the driver suddenly slaming on the brakes when they could otherwise have cleared the danger zone..

    1. Yes … a static object against an unchanging background is a recipe for camouflage. Movement is what catches the eye and a rider moving about in their lane is more likely to be seen. We still must take steps to be prepared to stop if necessary. Understanding the physical limitations of human eyesight and reactions can help us as riders navigate the hazards 🙂

  3. There was an earlier study which showed the ability to see was related to the perceived danger. They sent a bike a bike cop and a hells angel with a shotgun on their back down a hwy and counted how many times vehicles intruded into their space. Not much difference between the bike and cop. Guess which recorded zero intrusions!

    1. Ken – that study compared perception of a number of vehicles. “Cop car” rated as highest threat, followed by other cars, closely followed by “cop bike”, then “Bad Boy Harley”, perception/threat then dropped off sharply to leave “standard motorcycle” as least threat/easiest to ignore. My own observations(due to several years commute on the M1) bear this out somewhat.

Leave a Reply

Your email address will not be published. Required fields are marked *