To Understand Driver Safety, We Need to Understand Safe Driving

By Paul Atchley, PhD, eDriving’s Brain Science Advisor

Safe driving: It’s complicated.

In a recent webinar session with eDriving’s Jim Noble, we examined the “Triple Threat” of speeding, distraction and fatigue, and how these threats increase risk on the roadways. But understanding driving safety requires understanding more than threats to safety. We also need to understand safe driving itself.

We don’t give “safe driving” enough focus. Once we have been driving for years, it seems like a fairly simple task. But you may be surprised to learn that experienced drivers actually expend more mental effort to drive safely than novice drivers do. Safe driving is a set of effortful tasks. To understand the tasks that make up driving, I would like to introduce you to the SPIDER model developed by driving researchers Don Fisher and David Strayer.

SPIDER is shorthand for Visual Scanning, Hazard Prediction, Identification, Decision Making and Execution of a Response.  The model helps understand the many components that make up safe driving. Each is critical and they are all negatively impacted to some degree by threats like speeding, inattention/distraction and fatigue.

Visual Scanning refers to moving our eyes around our environment to permit detection of information critical for safe driving. This can include looking ahead, looking to the periphery, and scanning mirrors. It has been well established that these behaviors are worse in novice drivers. They also decline when we are distracted with eye-movements to the periphery, where many threats originate.

Hazard Prediction refers to glances to areas of the roadway to anticipate possible threats. For example, glancing toward a driveway in anticipation of a car entering the roadway as you approach is an example of hazard prediction. Hazard prediction is part of driver training and testing in some countries for good reason: it is one of the variables that shows a consistently strong relationship to crash risk.

Identification refers to the requirement to do more than “look” to actually see. Our eyes can fixate on an object, but unless our brain has sufficient resources to process what we have fixated, we do not understand or identify that object. This is one reason for the well-known effect of inattention blindness, in which we fail to “see” something in our field of view because we are mentally distracted. In other words, seeing requires your eyes AND a fully engaged brain.

Decision making refers to the fact that when we drive, we are often faced with options for what to do next. We can maintain or change our lane. We can make a turn or wait for traffic. We can slow down or stop completely. A decision then becomes an Executed Response. The decision/execution stage is one of the most challenging parts of driving. First, the decision/execution stage is one of the most bottlenecked processes in the human brain. Second, behaviors like speeding reduce driver options and the time to make a safe response. In other words, even if we scan, predict and identify a threat, we may not be able to avoid it.

In summary, driving is an incredibly complicated task. Driving seems like second nature to many of us but behaviors like speeding or driving aggressively, talking on a phone, or driving drowsy can negatively impact any number of processes critical for safe driving. A failure in any one of these important processes can be the difference between a safe drive and one that ends in tragedy.

About Paul Atchley
eDriving’s Brain Science Advisor, Paul Atchley, PhD, is the University of South Florida’s Senior Associate Vice President and Dean of Undergraduate Studies. As a Professor of Psychology, he specializes in research in cognitive factors, including the implications of multitasking on driving.