Why Do Drivers Sometimes Not “See” Motorcyclists? (Motorcycle Accident Reconstruction)
In March 2018, I wrote a post called “Why Do Drivers Pull Out in Front of Motorcyclists?” In that post, I reviewed and summarized 18 studies that examined factors that contributed to drivers not “seeing” an approaching motorcyclist and pulling into the motorcyclist’s path without sufficient time and distance to clear the motorcyclist’s path without causing a collision. Since writing that post, I’ve continued reading on this topic. Many times that has been frustrating…there is a lot of literature on the topic, but often this literature simply assumes a framework for setting up an experiment (i.e., motorcycles need to be more conspicuous) or simply rehashes the findings of the same group of core studies. It has been a while since I’ve found a write-up that has given me new insight or clarity on this topic. Admittedly, for the last year, I’ve been in the midst of starting a company (Luminous Forensics), and so perhaps I haven’t had the time to read as widely on the topic as I might have. Recently, though, I stumbled upon Chapter 3 from the book The Psychology of Driving by Graham J. Hole. This is a phenomenal chapter…so well written and insightful and a pleasure to read. I just ordered my copy of the entire book, and you should to…preferably from somewhere other than that one dominant tech-giant of online selling.
Here are some highlights from this chapter:
“Most relevant objects in the environment (such as other vehicles, and even pedestrians, most of the time) are well above the sensory thresholds and hence should be easily detectable. Nevertheless, a surprisingly common cause of accident is that drivers fail see each other, or see each other too late to avert a collision…”
“Why do these looked but failed to see (LBFS) accidents occur? The most obvious explanation is that the oncoming vehicle was hard to see, in sensory terms. This view appears to be supported by the fact that motorcyclists and cyclists are often the victims in this type of accident. It’s argued that these road-uses are small and hence difficult to see, and so it’s understandable that driver might fail to detect them while trying to emerge from a junction. However, a closer look at the evidence suggests that the real cause of this type of accident may lie not in limitations of the offending driver’s low-level visual system, but in more cognitive system involved in attention that are crucially affected by the driver’s expectations about what he is likely to see.”
I really like this analogy: “…a road sign giving route information might possess high levels of sensory conspicuity, in the sense that it is large, bright and centrally positioned in the driver’s field of view. For a driver who needs to know that route information, the sign might also possess search conspicuity: they are expecting to see a direction sign, and they are actively looking for that particular information. For a driver who knows the route well, the sign is irrelevant and may not even reach conscious awareness.”
“The studies described in this section suggest that drivers’ fixation patterns (and by implication, their allocation of attention) are highly dependent on past experience: driver know where to look, what to look for, and when to look for it. Top-down control of attentional allocation like this is highly efficient. However…it also carries a penalty - a strategy of looking for what you expect to find, may mean you sometimes overlook what is actually there.”
“…are motorcycles inherently difficult to detect? It is unarguable that they have a much smaller frontal area than a four-wheeled vehicle. However, being harder to detect is not the same as being difficult to detect. Motorcycles may still be well above sensory thresholds for detection. As mentioned earlier, claims that motorcycles are hard to detect because of sensory limitations rest heavily on drivers’ statements that they did not see the motorcycle. Precisely what a driver means when he or she say this is a little ambiguous. Such statements are interpreted as meaning that the motorcycle was not detectable, in sensory terms. However, an equally valid interpretation is that the motorcyclist was detectable, but that for some reason this information did not reach conscious awareness.”
“A second line of ‘evidence’ used to support the idea that motorcycles are deficient in sensory conspicuity is that conspicuity enhancements such as headlight use and bright clothing seem to make motorcyclists more visible to other road-users. Evidence to this effect is surprisingly poor.”
“If motorcycles are well above sensory detection thresholds, then why do drivers fail to detect them? As with most accidents, there are a number of possible causes, most of which are not necessarily mutually exclusive. Simple carelessness may sometimes play a part. Langham covertly filmed drivers emerging from a junction, and found that most spent very little time looking along the road they were emerging into: the mean was around 0.3 to 0.4 seconds. Some drivers did not appear to look at all.”
“Physical properties alone do not guarantee detection if the driver’s expectations and aims cause attention to be allocated elsewhere. The weight of the evidence suggests that many accidents attributed to sensory perceptual failures might be better characterized as being due to attentional problems…A failure to appreciate that sensory conspicuity does not guarantee conscious detection has led to a number of researchers going down a blind alley when it comes to researching the problem of motorcycle conspicuity, focusing on ways to make motorcycles brighter rather than trying to find methods of ensuring that motorcycles reach other drivers’ awareness.”
I could go on, but that’s enough to give you a flavor. This chapter is well worth a read.