Motorcycle Accidents: How The Brain Is To Blame

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Motorcycle Accidents: How The Brain Is To Blame

A recent psychological study has suggested that some motorcycle accidents are caused by the way the human brain perceives distances. This could explain why a vehicle turning left in front of you is the most common crash.

Texas Tech University professor Patricia Delucia is the author of the study entitled ‘Effects of Size on Collision Perception and Implications for Perceptual Theory and Transportation Safety’ that was published earlier this year.

The conclusion of the study was that often vehicle drivers couldn’t accurately judge the size of an object and how far away it is, which may explain the cause of some motorcycle accidents.

Delucia’s findings looked at fatal motorcycle accidents in the U.S. and established that more than 42 percent involved a similar set of circumstances: another vehicle turning left and colliding with an oncoming motorcycle.

The study, which was published in Current Directions in Psychological Science, looked at the relationship between an object’s size and the brain’s ability to judge the distance of that object.

Delucia’s research found that smaller objects are typically perceived by the viewer to be farther away than larger objects at the same distance. Because motorcycles are much smaller than cars, this perception error may interfere with a driver’s ability to accurately judge the distance of an oncoming motorcycle, particularly when the driver is about to make a left turn.

Potentially in this type of situation this makes collisions more likely to occur causing the driver to pull in front of a moving motorcycle because they think the bike is further away than it actually is.

Delucia said in her study: “People reported that a large, far, approaching object would hit them sooner than a small, near object that would have hit first. This effect of size on collision perception violates theories of time-to-collision perception based solely on the invariant tau and suggests that perception is based on multiple information sources, including heuristics (trial by error). The size-arrival effect potentially can lead drivers to misjudge when a vehicle would arrive at an intersection and is considered a contributing factor in motorcycle accidents.”

This essentially means that drivers have a hard time understanding the rate of speed, distance and size of an object, such as a motorcycle coming towards them. What Delucia’s study doesn’t offer are any suggestions on how to prevent this happening in the first place.

Either way, the knowledge is good to have as it may make you take that extra moment of caution when approaching vehicles prepared to turn into traffic—and as all riders know, every, single moment counts.

  • SniperSmitty

    Finally some scientific proof. I will be forwarding this to everyone I know. Thanks to RideApart for posting this.
    Keep the dirty side down riders.

  • Glenn Rueger

    No matter how ready you are for a left-turner there’s always that instant of vulnerability.
    For what it’s worth, I have perceived a noticable effect on drivers seeing and judging my oncoming speed since installing (Denali) LED running lights low on the forks.
    The famous “Triangle of Conspicuity”; like the 3 headlights on a train or the 3 brake lights on the rear of a car.

    • Kr Tong

      My theory has always been that cars are easier to spot because they look like faces, and we pick out faces in everything. Toast, clouds, dog’s buttholes (google it, actually no, don’t google it), and i read somewhere (now i can’t find it) that anything with a face is easier to determine direction of travel and speed.

      That said I just spent an hour looking for an NHTSA study or something to back me up and found NOTHING that said any faces, triangles, or really any arrangement of auxiliary lights benefits motorcyclists.

      • Glenn Rueger

        Of course my observations aren’t scientific but I believe that perception of speed is more obvious when the viewer can see the convergence of more than one point of light. With a single light there’s no convergence at all.

        • Kr Tong

          It apparently works better than having the aux. lights on the handlebars, but just as good as a flashing high beam. So there is some scientific evidence.

          I’ve had yellow/green and pink HID’s before and thought that they helped a bit. My thought was that they differentiated me from other headlights.

        • Mykola

          To my eternal embarrassment, I nearly ran a motorcyclist off the road a long time ago. It was a dark and lonesome night on a long straight highway in the middle of nowhere and, deciding to overtake the vehicle in front of me, I misjudged his distance (right on my a**) because the narrow spacing of his cruiser-style (horizontally arranged) auxiliary lights made him look to me like a car would from a half mile back. This is of course an exception (and as an isolated anecdote, doubly dubious for informing one’s view), but if he had just the headlight on, I would’ve recognized it was a motorcycle and paid heed to him accordingly.

          • Glenn Rueger

            I’m glad you managed to avoid tragedy. Another good reason to have the extra lights mounted low. My main light is slightly orange-ish in tint while the LEDs are brilliant white over which I have added yellow tint to the top halves only. I fancy a motorist would have to take notice at hight since it looks a bit like a UFO from Close Encounters.

        • Jack Scruggs

          This is what was running through my feeble mind.

    • Kr Tong

      Found the study:

      “Although the results of this study did not provide any evidence that the experimental lighting
      treatments on the motorcycle influenced the mean safety margin (judgment of the last safe
      moment to turn in front of an approaching motorcycle), there was evidence that the experimental
      lighting treatments significantly reduced the occurrence of short safety margins. This suggests
      that enhancing the forward lighting on motorcycles during the daytime may be effective at
      reducing the probability that drivers will turn in front of the motorcycle with an unsafe short
      safety margin. Potentially, this would reduce crash rates. In particular, the low-mounted set of
      auxiliary lamps (LA), the modulated high beam headlamp (MHB) and the four-lamp auxiliary
      treatment (LHA) were most effective at reducing short safety margins. Also, the results suggest
      that the conspicuity of the motorcycle as measured by participants’ looking behavior was
      increased, at least for a subset of the participants, by the LHA and MHB treatments.

      These results should be interpreted cautiously in light of the differences observed between
      subsets of participants in the study. In a post-study interview, some participants reported using a
      landmark strategy to judge when it was safe to turn by comparing the position of approaching
      vehicles to fixed roadside landmarks. Other participants focused on the approaching vehicles
      speed, the time until its arrival at the conflict point, or used other strategies. Differences were
      observed between landmark participants and non-landmark participants in the effects of the
      experimental lighting treatments. For participants who used a landmark strategy, the influence
      of the experimental lighting treatments was to reduce the probability of giving a short safety
      margin, while for non-landmark participants the influence of the experimental lighting treatments
      was to increase the time spent looking toward the motorcycle.

      Future research on motorcycle conspicuity and crashes resulting from right-of-way violations
      may benefit from an expansion in experimental paradigms from an emphasis on time/distance
      perception and perceptual biases revealed by measures of central tendency to the study of rare
      events including failures or delays in detection, lapses in attending to detected objects, individual
      differences in drivers’ perceptual strategies, and countermeasures for inattention blindness.

      Overall, the results from this study indicate that enhancing the forward lighting on motorcycles
      during the daytime may be a promising countermeasure for reducing “left turn across path”

      • aquatone

        Thanks for posting the study.

    • William Connor

      Watch the video I linked and the side to side movement of the motorcycle is far more effective than any 3 light theory.

    • Scott Jones

      I run a yellow (3000k) colored bulb in the headlight on my scrambler and I noticed an immediate reduction in getting cut off and pulled out in front of. I also noticed more people make room for me when I lane split on that bike than my 996 which is much louder and has yellow body work. I think it’s due to the light not being the same color as everything else so it naturally draw others eyes to it, much as the triangle pattern mentioned above or cars with drop in HID lights.

  • Kr Tong

    There’s been lots of tests on how to make motorcycles more conspicuous. The short of it is: move to canada.

  • 200 Fathoms
  • tbowdre

    Another reason California is such a great place to own and ride motorcycles… the left turn RED ARROW. The red arrow is pretty annoying as a car driver, that has lived in multiple other states in the US, but as a motorcyclist I love it.

    • Aaron

      Yes! this totally works.

    • cocoa classic

      The red arrow doesn’t exist in many intersections, like ones controlled by stop signs instead of lights.

  • Aaron

    The only thing better than the red turn arrow, the traffic circle.

  • Honyock Undersquare

    And yet, the most common excuse for the left turn in front of moving motorcycle is undoubtedly “I didn’t see him/her”. I suspect that poor time/distance judgements are 5% of the cause, and pure negligent inattention 95%.

    • Kr Tong

      Happened to me three weeks ago. Im dumbfounded to be reading about it and learning it’s the number one killer of motorcyclists.

    • Michael Howard

      Exactly. Cagers don’t say, “I thought he was farther away” – they say, “I didn’t see him”.

      • Kr Tong

        That might just be the incidents that end with an actual collision. There’s a number times where a car has pulled out in front of me and i had to slow down or brake. I always thought they just were being dicks but maybe they completely misjudged the speed.

        • Michael Howard

          True. What you describe happens to me regularly even though I have very bright dual headlights.

          • Kirk Roy

            I had the impression that dual (side by side) headlights make it even harder for cars to judge distance. The two headlights are interpreted as car headlights really far away. This is supposedly the reason for the dual headlight systems where, in low beam mode, only one of the headlights is on.

    • BigHank53

      One sentence that has stuck with me, heard from an MSF instructor: “Most drivers don’t see the car or truck that hits them. You’re a lot smaller.”

  • ThinkingInImages

    Anything coming straight at you is hard to judge. Think back to when you were a child and learned to catch a ball. You first instinct was to jump out of the way or cover your face. The same would apply to riding or driving until you learn how to deal with it.

    • BillW

      Yep. That’s why, when I know I’m in one of these situations, I’ll change my lane position or even weave in my lane a bit to generate some eye-attracting horizontal movement.

  • metalheartmachine

    Doesn’t this give proof to two headlights like eyes being better for recognition? I also remember a study that did find that excessively bright lights made judging speed/ distance very difficult at night.

  • William Connor

    All I have to say to this is “Duh”. This has been a fact known by most motorcyclists since I started riding almost 30 years ago on mini bikes. Here is one of the best ways to combat it.

    • BillW

      Good advice. I use some variation of this frequently, although seldom quite as extreme a maneuver as shown in the video. But a little wiggle, or a change from one side of the lane to the other, is easy to work in without causing problems with other traffic that you’re not working about.

      • IAmAConservativeICannotBeWrong

        The driver is just as likely to ignore it because it’s unexpected movement. The mind will just dismiss it.

        The bigger problem is that the driver probably has bad eyesight in the first place.
        Assuming that they are driving legally ;) in my state a driver need only have their vision checked once every 5 years now,

        and then they only need to pass the vision test IN ONE EYE.

        And on top of that the older the driver, the longer it takes them to change focus-distance.

        But beyond taht they simply could e distracted, in a rush, not expecting a bike not worried about a bike…all things that can

        keep them from even thinking about a bike until you crash into it. If…you crash into it. But there’s no excuse for crashing into a car.

        The thing is that you have to assume that the driver just does not see you and will pull out right in front of you, until you get some positive indication that they DO see you and they will NOT pull out right in front of you.

        I like to slow down and wait until I see them start to pull out, see me and then stop.

        Then I know they see me and they are going to wait until I pass.
        If they get pissed because I pass them slowly, and when I pass them I can see them seethe, that’s fine.

        As long as they don’t hit me. And eventually they will realize that.

  • AHA

    I’ve read elsewhere (Bike magazine in the UK I think) that a potentially major perceptual issue is that a motorbike (or similar smaller frontal area object) approaching near directly towards an observer will not be picked up as quickly as an object moving across the observer’s visual field of perception. The eye sees it but the brain doesn’t prioritise it because it’s not apparently changing position or shape very much. The brain optimises its visual processing by looking for changes in the visual field. A bird of prey uses this to its advantage, stealing up quickly on its prey by approaching in a direct line and reducing its frontal areas as much as possible. A motorbike is particularly vulnerable to this ‘blindness in plain sight’ effect due to the relatively high closing speed compared to its perceived change in shape and position as observed from near straight ahead. This is particularly a problem at night where the single headlight of a bike will likely be lost against the myriad headlights of the following cars. Daylight ain’t a whole lot better, particularly as most car drivers are scanning for vehicles i.e. cars and lorries, not motorbikes or bicycles and as we all know, in life we tend to see what we’re looking for, right? A possible solution is to break the ‘continuity of vision’ by waggling the handlebars so the headlight moves side to side slightly, or even weaving smoothly & safely, as you approach oncoming vehicles waiting to turn across your path.

  • NextTurn

    This is why I typically cycle my lights and use the full width of a lane to show 1) that a moving object is headed your way, and 2) that it is moving fast enough to make rapid movements. I short zig-zag in the lane while flashing your high-beam briefly usually has people stopped long enough to stare while I pass through the intersection. It doesn’t always work, but I believe it has helped me out more than once.

    …of course, this is all completely unscientific, and may be all in my head.

  • IAmAConservativeICannotBeWrong

    this is nonsense psychobabble

    A driver who is responsible for hitting an oncoming motorcylist?

    LOL the driver is never responsible for this.

    The motorcyclist is.

    If you are on a bike approaching someone in a car and they hit you?

    Whose fault do you think that is, theirs or yours?

    oh, “they miscalculated your speed, distance and the time it would take you to reach them” DUH
    That’s all fine well and good. Doesn’t take a rocket-scientist to realize that estimates of your speed, distance and time of arrival are going to be wrong.

    But if you let them hit you, that’s your stupidity, not theirs.