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New research shows drivers ‘see but forget’ motorcycles

By Mario

Just as we complete Motorcycle Awareness Month, Nottingham University finds another reason why accidents with other vehicles are so common.

Research scenario

Although the most serious motorcycle crashes tend to be single-vehicle endeavours (often when a rider fails to take a bend), collisions with other vehicles are the single most common. One we’re probably all familiar with is the ‘SMIDSY’, where a driver pulls in front of an oncoming motorcycle, offering the predictable apology of ‘Sorry Mate, I Didn’t See You.’

It’s easy to be dismissive and think the driver just didn’t look properly, but we’ve looked into this issue before with some surprising results. When we kicked off Motorcycle Awareness Month last year, we touched on the phenomenon of ‘saccadic pausing’. This is where our brain and eyes work together, bringing what we think is seamless, flowing vision. The reality is somewhat different, with our brains stitching together a series of snapshots, with pauses where the image is processed by the brain, then the brain fills the gaps. When your eyes are moving, your brain actually blocks the image data it’s receiving. This alone has all sorts of scary implications for riders expecting to be seen on the roads.

Other issues were recounted by Kevin Williams of Survival Skills, when we interviewed him for Bike Rider Magazine prior to his second year appearing at Shiny Side Up. Alongside ‘Visual Motion Camouflage’ and the very narrow range of clear, coloured focus in human vision, Kevin covers the whole ‘Science of Being Seen’ as a topic in itself.

Now we have another factor to add to our knowledge of why drivers do not take account of motorcycles when maneuvering: the ‘Saw But Forgot’ phenomenon. Conducted by researchers at the UK’s University of Nottingham, their study used a high-fidelity driving simulator. Respondents were subjected to a series of typical driving scenarios where they had to look for approaching vehicles before maneuvering. Drivers failed to report oncoming motorcycles in 13% to 18% of occasions, despite fixating directly on the approaching bike. This was around four times higher than failures to report cars, and close to eight times those for goods vehicles. Lack of reporting seemed to be most closely associated with the subsequent length of time and amount of visual searching that occurred before maneuvering–but we’re only talking fractions of seconds, here.

The research team, led by Dr Peter Chapman, refers to previous studies that equated the high crash risk of motorcycles in these circumstances as being due to the ‘size-arrival’ effect, which suggests small objects like motorcycles are perceived as further away. This study doesn’t conflict with that, rather it provides greater understanding of why so many motorcycle crashes are caused by drivers who ‘look but don’t see’. It seems, even when an approaching rider is seen, the storage and retrieval process involving short-term memory may be prone to failure. As to why motorcycles do so much worse than cars, the researchers suggest this may be caused by widespread mis-reporting of how far away the motorcycles were. Respondents almost always reported the location of motorcycles as further away than they really were.

Although the most serious motorcycle crashes tend to be single-vehicle endeavours (often when a rider fails to take a bend), collisions with other vehicles are the single most common. One we’re probably all familiar with is the ‘SMIDSY’, where a driver pulls in front of an oncoming motorcycle, offering the predictable apology of ‘Sorry Mate, I Didn’t See You.’

It’s easy to be dismissive and think the driver just didn’t look properly, but we’ve looked into this issue before with some surprising results. When we kicked off Motorcycle Awareness Month last year, we touched on the phenomenon of ‘saccadic pausing’. This is where our brain and eyes work together, bringing what we think is seamless, flowing vision. The reality is somewhat different, with our brains stitching together a series of snapshots, with pauses where the image is processed by the brain, then the brain fills the gaps. When your eyes are moving, your brain actually blocks the image data it’s receiving. This alone has all sorts of scary implications for riders expecting to be seen on the roads.

Other issues were recounted by Kevin Williams of Survival Skills, when we interviewed him for Bike Rider Magazine prior to his second year appearing at Shiny Side Up. Alongside ‘Visual Motion Camouflage’ and the very narrow range of clear, coloured focus in human vision, Kevin covers the whole ‘Science of Being Seen’ as a topic in itself.

Now we have another factor to add to our knowledge of why drivers do not take account of motorcycles when manoeuvring: the ‘Saw But Forgot’ phenomenon. Conducted by researchers at the UK’s University of Nottingham, their study used a high-fidelity driving simulator. Respondents were subjected to a series of typical driving scenarios where they had to look for approaching vehicles before manoeuvring. Drivers failed to report oncoming motorcycles in 13% to 18% of occasions, despite fixating directly on the approaching bike. This was around four times higher than failures to report cars, and close to eight times those for goods vehicles. Lack of reporting seemed to be most closely associated with the subsequent length of time and amount of visual searching that occurred before manoeuvring–but we’re only talking fractions of seconds, here.

The research team, led by Dr Peter Chapman, refers to previous studies that equated the high crash risk of motorcycles in these circumstances as being due to the ‘size-arrival’ effect, which suggests small objects like motorcycles are perceived as further away. This study doesn’t conflict with that, rather it provides greater understanding of why so many motorcycle crashes are caused by drivers who ‘look but don’t see’. It seems, even when an approaching rider is seen, the storage and retrieval process involving short-term memory may be prone to failure. As to why motorcycles do so much worse than cars, the researchers suggest this may be caused by widespread mis-reporting of how far away the motorcycles were. Respondents almost always reported the location of motorcycles as further away than they really were.

Model of how the brain processes images

As a driver scans for a gap in traffic the brain constantly churns through the PRC model, discarding ‘unimportant’ perceptions.

This would seem consistent with the ‘size-arrival’ effect. Drivers perceive bikes to be further away. So, as the brain is going through a constant process of perceiving information, selecting what to retain then choosing what to discard in order to continue the process (Perceive, Retain, Choose or PRC model), motorcycles get discarded more often because they are perceived as further away. To the brain, they represent less of a risk so they are more readily forgotten–an inbuilt bias.

As an inherent human failing, countering this issue to improve safety is not an easy task. But understanding it is an important first step. For we riders, it’s another thing to take into account when we approach vehicles that may move into our path. For drivers, recognising the potential failing is a start. It may be that simple memes which can ‘jog’ the short term memory–such as saying ‘bike’ aloud when one is spotted–will help. It also tends to support the value of things like Motorcycle Awareness Month: if it can raise some drivers consciousness about motorcycles on the road it may just help them remember that they actually have seen us.

Link to paper by Chapman et al published in PLOS One

February 2019 issue of BRM featuring interview with Kevin Williams

Kevin Wilson’s Survival Skills on Facebook