The common conception of smartphones and tablets these days, partly from advertising, is that they are flat slabs of glass, as thing as possible. Everything happens on the screen.

IMAGE OF PHONE/TABLET FROM SIDE A. LA. MANY ADS.

But even if phones become infinitely thin, people are three dimensional.

IMAGE OF FINGER TOUCHING SAME PHONE IMAGE.

People use their phone in real environments, so we must set aside the assumption that the interaction is entirely with a flat glass screen. The way people hold and tap changes by their grip, and that changes because they are carrying items, talking to others or opening doors.

Environment

As discussed above, people shift how they hold and touch their devices based on the device, the input required, the position on the screen they are trying to tap, and context, but what contexts? I have observed people changing how they hold their phones when:

• Opening a door.
• Carrying groceries.
• Carrying a baby.
• Walking.
• Walking in difficult terrain, or stepping off a curb.
• Riding on a train or bus, especially standing.
• When near danger, such as wind, water or a dropoff.

PHOTO OF LILY WITH BABY?

These changes only allow the user to keep ahold of their phone with some confidence, and basically manipulate it, but in some cases the results are still poor. For example, when ...talk about the study on how accuracy changes when carrying things. Specifics, with images of inaccuracy, etc...

Empathy

When I talk about findings like this, many people throw their hands up and pretty much say we should just design for ideal cases. Why not assume that the half the people who hold their phone with one hand are our baseline, likewise just assume they are standing still and staring at the screen, and all other users can muddle through or change their behaviors.

Of course, this is anti ethical to my favorite principle of UX: empathy. We must not rant about device fragmentation, or ignore behaviors different from our own. All that does is blame the user for their natures, and dismiss their unique goals and needs.

Instead, we have to embrace complexity and design to accommodate the messy lives users live.

LEAD IN MORE??? Everything you do is too complex to adequately model and map. Assume you have always missed something, so you are prepared to deal with the unexpected, both in design and so you can modify your product over time to take advantage of new ways you find people using your information. OR MOVE THIS TO LATER???

Resilience

Resilience engineering is a practice of XXXX COPY FROM WHERE I WROTE THIS???

I say there’s something called Resilience Design. Or there should be. Here’s a simple example…

I also still wear normal watches. One is a dive watch as shown in figure X, because it’s shiny, not because I am a diver or anything. It is one of those with a twisty ring around the outside. That part with the numbers twists around.

PHOTO OF MY WATCH. TAKE A NEW ONE. ON BLACK AND ON WHITE.

If you don't know, and I didn't until after I actually owned one then looked it up, this is used as a simple timer. But on mine, and on all dive watches, the ring only goes one way, limited by a detent. On aviators watches, there is no detent. Why is that? Because it's for timing remaining air. The ring might get bumped and change it's setting. Having it show less time might be inconvenient, but going the other way might kill you. And, you don't even need to know this. It just works. That's the sort of brilliantly-simple answer I am talking about with resilient design.

You need to make your designs resilient because users will never, ever do what you expect. You, or others in your organization, probably draw diagrams that assume everyone starts at the home page, drills down through a preferred path and gets their information.

It’s not true. People bookmark, share, and search. They use your process in unexpected ways, and your system returns errors or data you didn’t expect. If you try to design to accommodate these, or to test for them in the traditional use case model, you CAN’T. For one project I worked on, I did some quick math and to create the use cases for all variations would take approximately the remaining life of the universe.

Really.

These are arbitrarily complex products, so don’t lament but embrace the complexity.

??? TOO MUCH PAST THIS. MOVE ON... On a typical website, I find that home page as the entry point is rarely over 10%, and is often so low as to be ignored; hundreds of visits a month when hundreds of thousands visit the site.

This is even more important with the way people engage on mobile devices. People seek out and consume content sometimes a few seconds at a time. They get interrupted, and come back to read a bit again so it has to be ready for them. Does your information work well and make sense if set aside for a few minutes? A few hours? Make sure session expiry and other technical things don’t get in the way of users coming back.

And, remind them to come back. Use SMS, and app notifications or reminders within the site or app of items that may be interesting or that they didn’t complete. Or emails. Or postcards. Or whatever fits the way you have a conversation with your customers or users.

Accessibility for Everyone

All people are, as Robin Christopherson says, temporarily disabled, and designing like this can assure your mobile device works for every user all the time. We work in loud environments, with glare and rain, cannot touch the device, are distracted. Subtle cues may not work, so multi-encode indicators and responses to interaction.

ALSO ALL THE NUMBERS ABOUT EVERYONE BECOMING LEGIT DISABLED EVENTUALLY, INFO ON THINGS LIKE COLOR DEFICITS BEING DISABILITIES ALSO... DON'T ASK YOUR CLIENT IF ACCESSIBILITY IS PART OF THE FEATURESET, IT ALWAYS IS.

???

... some basic guidelines on notifications, but make sure we do not stray too far afield. This is about touch, but make sure it's about sense at least...

...So, wait for users, don’t pop up messages for short periods, don’t beep if they are likely to be in loud environments. Maybe even Christopherson’s Temporary Disability, and touch on how you must design also for low-vision but designing for real environments gets you a long way there…

Don’t Forget Cases and Bezels

Despite the increasing prevalence of edge gestures, dragging items on or off the screen, we have to remember that touchscreen devices are literally not flat as well.

Plenty have a raised bezel to protect the screen, and many, many users put cases on. What this means is that many users cannot actually get to the edge of the screen. If they really press their finger they can get skin onto the edge, but remember the screen senses the center of your contact area so even if you can push your finger hard enough to get to the edge of the screen, the sensed point may be well inside the edge.

If you want to place items right against the edges, or have edge gestures, go ahead. But don’t only allow them to work at 1 pixel from the edge, or originating off screen. Provide some padding.

The safe zone here is somewhere between half and the full width of the accuracy by zone. Along the sides, I use 6-8 mm, but for the top and bottom I would extend this to about 10-12 mm.

...Segue to the next section on designing at scale. Design /for/ people then design /like/ the way people work.

References

• Investigating the Effects of Encumbrance on One- and Two- Handed Interactions with Mobile Devices DOWNLOAD p1981-ng.pdf
• resilience...
• empathy in ux...