Given the complicated process that occurs inside us in order for us to see, it's amazing we're able to operate motor vehicles at all.
Many gamers are familiar with the concept of the digital worlds we play in being a 3D model of the landscape, characters and objects you encounter. If you're on a monitor you're merely looking at it through a window, but it really is a 3D model built to life size and displayed to scale. Players with virtual reality headsets can trick their minds into believing they're really in that place and situation (a desirable state called immersion).
We kind of do the same thing in our brain with the physical world. Researchers have done various experiments to demonstrate that we only take in very specific visual information that we're concentrating on. Other details, sometimes right in front of us, are frequently missed.
There's a famous experiment from 1999 known as The Invisible Gorilla, designed to test selective attention. In a short clip, six people are passing basketballs. One team of three is wearing white shirts and the other team are in black shirts. You're told to count the number of times the team wearing white passes the ball. Most people get the right number, or they're close, but about half totally miss the person in a gorilla suit that walks into the middle of the players, beats their chest a few times, then walks off.
The researchers, who wrote a book called The Invisible Gorilla: And Other Ways Our Intuitions Deceive Us, said "This experiment reveals two things: that we are missing a lot of what goes on around us, and that we have no idea that we are missing so much."
About 10 or so years later the same researchers published other versions of the same test. By this time people were expecting the gorilla and saw it, but they instead missed other significant changes on the screen. Their aim in that video was to demonstrate that even expecting unexpected events does not necessarily make people better at noticing any of the actual unexpected events.
The conclusion drawn from this and other studies, is that most of what we think we see is actually just memory, with certain details we notice refreshing that 3D model in our mind, and our location within that model.
The gorilla experiments were deliberately blatant with large details, but for centuries magicians have exploited our propensity to disregard all sorts of information our brain doesn't think is vital. They simply draw your attention to one thing that isn't part of the trick, and your brain naturally filters out the rest. But without that filtration, we wouldn't be able to concentrate on anything.
Think though, about what this natural filter means when you're driving. Even when you think you're concentrating, you can still miss quite a bit. And there's a lot to see, from other drivers and riders around you, to pedestrians, animals, various road signs, and of course, the road to where you're going.
Studies on consciousness have found basically the same thing. That is, we create a low-resolution interpretation of the world around us, and impose our perceptions upon various objects. It's the reason we can anthropomorphise puppets, even when we can see the ventriloquist's arm. And that illusion still doesn't get broken when they make a joke about where their hand is.
Apart from the sheer amount of data that would need to be constantly updated, another reason for the low resolution of that 3D model is the narrow band of visual acuity. Your vision is only sharp at a small point in the centre, about seven degrees, and gets much lower in resolution towards the periphery. That periphery is up to 120 degrees, but it also narrows with age. Plus we rely on stereo vision to help with depth perception.
We also know that the eyes move in ways that aren't nearly as smooth as we perceive, even when you're reading. They don't pan gently like a well-operated camera. And complicating it further, your visual attention can shift even without the eye moving.
So, if you think you can divert what little attention you do have to distractions inside the vehicle like smart devices, you're very sorely mistaken. You barely see anything as it is.
Sam Hollier is an ACM journalist and a motoring fanatic who builds cars in his shed in his spare time.