Braille at the Edge of Sight – The Driver’s Experience

Peripheral vision does not get much fanfare, though it is essential for survival. I learned this from a reality TV show on what to do while walking through the African bush country at night. It’s easy to take for granted what we see at the edge of sight because peripheral awareness is often semi-conscious; that is until a snake falls from a tree or a car veers into one’s lane.   Furthermore, peripheral vision interacts with other senses such as touch continually in all our navigations, like when we walk and the ground meets our feet or when we reach out to hold something, like a crack in a cliff. Understanding how senses work together can also be helpful in the design of a vehicle’s human machine interface (HMI) and can make it easier to find controls and reduce distracted driving.

Peripheral vision has characteristics that deserve special consideration. Although we are naturally more aware of our central vision,  the different parts of our retina work in tandem and have complementary differences. Peripheral vision often seems to run in the background and less consciously, but draws in your central vision when it recognizes something worth seeing more fully. Peripheral vision depends on the outer parts of the retina and senses the world differently than the central retinal or fovea, which seems to have most of our attention. The table below summarizes the features of the 2 parts of the retina.

Peripheral Vision Central Vision
Less detail Detailed sight
Reduced color vision Optimal color vision
Lacks depth perception Sees in 3D with 2 eyes.

 

Dashboard controls, like the volume knob, may be first recognized peripherally before central vision watches one’s hands reach for and touch the control. This takes one’s eyes off the road and is distracting and possibly dangerous. An alternative is to keep one’s gaze forward and use peripheral vision to guide one’s  reach and  contact with a target. Certain things make this exercise easier such as good target

1)    peripheral visibility, because of its size and illumination.

2)    accessibility, because it is easy to reach or close to one’s hands and fingers.

3)    tactile features, distinguished by its size, shape, protrusions, depressions, and temperature.

To illustrate these concepts, consider the following scenario. I  was driving  at night on a dark and busy street in LA and wanted to change the radio volume and station. I needed to keep my gaze forward (at label A with the yellow outline of my sunglasses). Some controls (at lower right and labelled B)  were easy to see in my peripheral vision because they were large, round and illuminated. This also made it easy to reach  and feel them without looking  away from the road. In contrast, the radio station selection buttons  (yellow, dotted rectangle between top B’s) lacked tactile distinguishing features, were small and were hard to see. In this case, prolonged central gaze was needed to distinguish one button from the other.  As an analogy, my finger launched like a rocket from the steering wheel, relied on peripheral vision to navigate my hand  through space, and was able to make an accurate  touch done because of the distinctive tactile structure of the target landing pad. 

The senses of touch is very important. Akin to using Braille because of blindness, even the sighted need to to use their fingers to “see” the world because of low ambient light or  because machine controls are not where where one is looking.  Consider the moto, “eyes on the road, hands on the wheel”.  Controls with distinctive tactile or haptic features help  guide selection of menu items on a computerized heads up or windshield display  so the eyes can stay forward as much as possible. This video demo shows how to accomplish this ideal and also employs menu  integration with haptic controls.

Braille at the edge of sight is not such an abstract an idea after all. It helps keep us safe while driving. With this in mind, you may want to look at the controls in the cabin of your vehicle and see whether their design and layout makes sense to all your senses.

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Source of the image of the eye: Hans-Werner Hunziker. Hans-Werner34. https://upload.wikimedia.org/wikipedia/commons/3/39/Double_system_e.jpg

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