How Saccadic Masking Affects Driving

Our eyes move incredibly fast when shifting gaze from one point to another, for example, from left to right. This rapid eye movement is known as saccadic eye movements, also referred to as saccades. These rapid, jerky shifts in eye position occur as we scan the environment around us.

Due to saccades being so fast, they create a challenge: During the high-speed movement, the image on the retina blurs. These movements are essential for helping us when reading and following moving objects, as well as scanning roads while driving. We have blind spots during a saccade, which means we are momentarily blind to new visual input. We often overlook this gap because our brain seamlessly integrates information from before and after it. This is where saccadic masking comes in.

How Saccadic Masking Works.

Saccadic masking or saccadic suppression is the brain’s ability to block out visual information during a saccade. Even light or other stimuli that hit the retina during a saccade can go unnoticed. Our perception of the world would be a dizzying blur without this visual stabiliser, therefore, creating a smooth and stable visual experience. Although we may think we have seen all the information around us, we haven’t, due to the brain editing the information we receive. What we see is what the brain allows us to see.

Impact on Driving.

Saccadic masking has practical implications where road safety is concerned. Quick head and eye movements at junctions can lead to saccadic masking, causing drivers to miss crucial visual information. Objects and vehicles can be missed, and motorbikes and cyclists can be obscured during these brief moments of visual suppression, making them particularly vulnerable. Driver fatigue and low-light conditions can exacerbate the effects of saccadic masking, thereby increasing the risk of missing hazards.

According to Bournemouth University and DocBike, ‘A research project exploring motorcycle collisions and injury prevention has found that there are differences in motorcyclists’ and car drivers’ visual attention because they may be viewing completely different things despite being on the same stretch of road. For example, the brain naturally sees larger objects, like lorries, as threats as opposed to smaller objects such as motorcycles. To help improve awareness and encourage safer driving habits, it is important to understand this phenomenon.

The project, led by Bournemouth University’s PhD researcher Shel Silva, was match-funded by DocBike, assessed the neurological and cognitive influences of motorcyclists and car drivers. Data indicates that car drivers and motorcyclists have different visual attention patterns, due to the different types of hazards according to the vehicle type. Additionally, motorcyclists’ identification, perception, and knowledge of potential risk changes depending on their motorcycling qualifications and experience.’ https://www.bournemouth.ac.uk/news/2022-01-24/bu-docbike-research-suggests-motorcycle-collisions-could-be-caused-riders-car-drivers-seeing-different-things?utm_source=chatgpt.com#:~:text=A%20research%20project,qualifications%20and%20experience.

Observation at Junctions.

Failing to make effective observations at junctions has been the number one reason for test failures for many consecutive years. I’ve often wondered why this is the case and who/ what is to blame.

Outside pressures such as impatient drivers and learners also feeling under pressure not to hinder others can be a factor as to why they may make a rash decision to emerge from junctions, or enter a roundabout when it’s not safe, especially when having the added pressure of an examiner sitting next to them and they don’t want to be perceived as being hesitant.

A while ago, I heard about saccades and saccadic masking and how this can affect the way we perceive what we see. Upon further research, it becomes clear that this could be a significant contributing factor to the failings.

Quick head and eye movements at junctions can lead to saccadic masking, causing drivers to miss critical visual information, such as cyclists, motorbikes, pedestrians stepping out, or changes in traffic signals. To ensure comprehensive scanning at junctions, it is important to pause at three different points to make deliberate eye movements. These three points should be left, directly ahead, and to the right to allow you to check long, middle, and short distance. Always look at least twice to ensure it is safe before emerging. Tailors and joiners measure twice and cut once. Drivers should look at least twice and go once. Only when safe to do so.

When we pause, it gives our eyes and brain a chance to identify a moving vehicle/person and work out distance and approaching speed. When identifying the object, we are able to acknowledge it and determine whether it’s safe to proceed. The results could be devastating if we don’t supply our brain with this information in the first place.

Rapid eye movements are more likely to occur when driving at night or in low visibility conditions. There is greater potential for undetected hazards as visual cues are already diminished. This is also increased when a driver is fatigued.

The UK Parliament has acknowledged that saccadic masking may contribute to accidents where drivers fail to look properly.

Research suggests that up to 25% of such accidents could be prevented with proper driver training to mitigate saccadic masking effects. UK Parliament Committees.

Moving forward, it is important to ensure that all new drivers are taught to pause at a central point in between looking left and right when observing at junctions and looking at least twice before proceeding when it is safe.

To test saccadic masking for yourself, try looking at your eyes in a mirror and look from one eye to another; you won’t be able to see your own eyes moving unless you film yourself while doing it.