Written by Dr Marc Green & John Senders
“Carriages without horses shall go,
And accidents fill the world with woe.”
-Mother Shipton (circa. 1530)
A comprehensive study of road safety (Treat et al., 1977) found that human error was the sole cause in 57% of all accidents and was a contributing factor in over 90%. In contrast, only 2.4% were due solely to mechanical fault and 4.7% were caused only by environmental factors. Other studies have reported similar results.
Why do humans make so many driving errors? The answer is that they don’t. Humans have limited information processing abilities and must rely on three fallible mental functions: perception, attention and memory. When a driver fails to avoid an accident because the situation exceeds these limitations, it is often called “human error.” In reality, it is often the situation that is primarily responsible, not the driver’s response to it. It is a well known bias of human judgment to commit the “fundamental attribution error,” to vastly overrate human factors to vastly underrate situation factors when trying to explain why events have occurred.
In this article, I shall provide a brief overview of human information processing limitations and explain how they can interact with situational factors to contribute to road accidents. This is a “first-principles” approach to accident investigation because it draws on knowledge of basic human psychological processes. Instead of looking at the driver from the outside, I try to understand his/her mental processing and how it interacts with the environment.
However, the overview is general, so I will ignore many details and equivocations that would be required in a more scientific dissertation. Moreover, the article will discuss only information processing and leave response, reaction time, etc. for another day. Lastly, although cast in terms of road accidents, a similar analysis would apply to other areas of man-machine error.
To read more of Dr Marc Green’s article, click the link below.