Designing for the aging eye is difficult and not just in terms of layout and readability. It's not just an eye you're designing for, it's a whole person. The go-to solution has often been to just blow up the size of the fonts and enrich the colors, winding up with something that looks more at home in a Fisher Price play-set than in a car. However degraded the eyesight of a senior citizen might be, they can see right through that.
We wanted to create a display that solved a problem for a specific set of people, but whose solution also works for everyone else. We wanted it to be universal.
In preliminary talks with aging drivers, we found that one of the things they have the hardest time with is knowing whether they're at the right speed. This comes as no surprise to anyone who's been stuck behind a boat of a Cadillac going 10 below the limit. But instead of thinking about it in terms of showing this data or that, we thought about it in terms of a question. Just how do I know whether I'm above or below the speed limit?
We started by looking at how aboveness and belowness are currently represented and broke a speedometer down into its constituent elements. When you look at it like this, it's not hard to see why someone with poor vision might have a hard time reading information presented this way. The difference between current and optimal is an angle, the optimal is constantly changing.
So we thought about how aboveness and belowness might be better displayed. One thing the eye is good at, even later in life, is recognizing equilibrium (and especially when things are out of equilibrium).
Old steam train manufacturers knew this too. An engineer didn't have time to check to see if each of the dozens of dials were at their own specific optimal, so the dials were arranged so that if a readout was in the optimal position, it pointed straight up. That way, all the engineer had to do was scan the dials and if he saw anything out of alignment, he knew where to investigate.
So we used this. We used the eye's natural inclination for alignment and equilibrium and designed a display that represented the essential information.
The display format, skin-able across brands, uses the center of the display as it's equilibrium point and the two elements on the side act as indicators. Using GPS data to gather speed limit data for the road you're currently on, If the indicators are at the center, you're at the right speed.
As you begin to speed up, however, the indicators move up as well, breaking their alignment and increasing their saturation.
And the same thing happens as you decelerate below the speed limit.
This way, drivers always are presented with the information they need, no matter how old they are.