Why the type on your parent's screen is so big

The first thing anyone notices about the senior side of Marlow is the size of the text. Next to the family side it looks almost like a different product. That’s on purpose, and the reasons are in the optometry textbooks rather than in anything we discovered ourselves.

This is the second of four posts on the research behind the senior screen. It’s about eyes.

Near focus goes first

Presbyopia is the loss of near focus. It starts for most people in their forties, around the time the arm holding the menu gets longer, and it is close to universal later on. Reading glasses exist because of it, and they fix it. If your mother wears hers, presbyopia is not the reason the type is big.

The reason is where the glasses are. A phone gets picked up on the way past, in the hall, with the reading glasses on the kitchen table. Big type is a hedge against that moment. Big enough that a time and a name can be read at a glance rather than studied.

The lens yellows and lets in less

Then there’s the part glasses don’t fix. With age the lens of the eye yellows and passes less light through, so the same screen looks dimmer and warmer to a 78 year old than it does to her son. Contrast sensitivity falls, which means the difference between a light gray and a slightly lighter gray, perfectly visible to a young designer, may simply not be there. Glare takes longer to recover from: walk in from a bright hallway and the page stays washed out for a while. And older eyes need considerably more light than younger ones to read the same text.

Cataract sits on top of all that and becomes common with age. Even before surgery it scatters light and pulls contrast down further.

None of this is unusual. It’s a common state for a pair of eyes in their seventies, and it’s the state we designed for. Not the eyes of the person doing the designing.

But eyes in their seventies vary far more than eyes in their thirties. A parent who has had cataract surgery may see better than her children. A parent with macular degeneration is losing the center of the view, and past a point size and contrast help less than someone reading the screen to her. If your parent’s vision is beyond what bigger, darker text can fix, this screen isn’t the answer on its own, and we’d rather say that here than have you find out on her counter.

What the guidelines say the minimum is

WCAG, the Web Content Accessibility Guidelines, is where most designers get their contrast numbers. It asks for at least 4.5 to 1 between text and its background for normal sized text, and at least 3 to 1 for large text. Those ratios were set for a broad population. A great many apps miss them anyway, usually with pale gray captions on white, because at a desk under good light and in your thirties it looks refined.

The word to notice is minimum. Meeting 4.5 to 1 means text most people can read under reasonable conditions. It says nothing about a dim living room or a lens that has yellowed.

Why the senior side goes well past it

On your parent’s screen we treat the WCAG numbers as a floor to clear with room to spare, not a target to hit. Dark text on a light ground, and no captions in a gray that only just passes. The type starts large and follows the phone’s own text size setting, and you can set it larger again from your side. Nothing on that side is styled to look delicate.

The same information appears on the lock screen and in a home screen widget: when to be ready, and who’s coming. Those are the surfaces she’ll glance at rather than read, and a glance is where a marginal contrast fails first. So they get the same treatment as the screen itself.

There’s a second reason for going past the minimum that has nothing to do with the guidelines. Text your parent can read comfortably is text she’ll actually read. Text she has to work at is text she’ll ask someone else about, and then the phone on the counter has become one more thing a daughter gets called about.

Why the family side is a different size

The family side of Marlow is set at an ordinary adult size. It’s a working tool for the people adding appointments and claiming rides, and they need a week on screen at once. Making it as large as the senior side would turn the schedule into an endless scroll.

But “ordinary” is doing some work in that sentence. The people coordinating a parent’s care are usually well into the years when reading glasses stop being optional. So the family side is still set larger than most of the apps you’ll have on your phone. The senior side is bigger again.

Two sizes, then. A screen for someone doing a job, and a screen for someone reading a single fact from across a room. The senior side page shows them next to each other, and the size difference is the first thing you’ll see.

What we don’t know

We haven’t measured any of this. Marlow runs no analytics, so we can’t see whether your mother squints at it or reads it without thinking. We ask families instead, and the parents using it tell us when something is hard to read.

The check that matters is one you can do in an evening. Hand her the phone in the chair she actually sits in, under the lamp she actually uses, with her glasses wherever they usually are. If she reads the time and the name without leaning in, it’s working. If she doesn’t, tell us. The size was chosen from the published guidance, and the guidance is a starting point, not the last word on one particular pair of eyes.