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 to keep basically manipulating it. People don't generally stop using their devices regardless of inconvenience, regulation or social convention. They just adapt to the situation, but do suffer consequences. Setting aside train and car crashes, simply carrying a bag of groceries reduces accuracy in ways I found unexpected. Ng, Brewster and Williamson found that touch accuracy in the distant corner could be off by as much as XXX, as shown in Figure XX.

IMAGE REPRODUCING p1981-ng.pdf TOUCH CHART - OVERLAY ON HANDSET FOR RELATIVE POS, TO MEASURE ACCURACY.

It was better when a second hand was used, but still different from not carrying anything. In my contextual observations, people do keep up with their normal lives and spend a lot of their time on mobiles while doing normal things. XXXX

Accessibility

ALL THE NUMBERS ABOUT EVERYONE BECOMING LEGIT DISABLED EVENTUALLY, INFO ON THINGS LIKE COLOR DEFICITS BEING DISABILITIES ALSO...

But more importantly, all people are--as Robin Christopherson says--temporarily disabled. Considering the accessible use case can assure your mobile device works for every user all the time. We use our devices in loud environments, with glare and rain, cannot touch the device, are distracted. Subtle cues may not work, beeping or blinking may be missed. so multi-encode indicators and responses to interaction.

... 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...

MOVE RECOMMENDATIONS TO THE RESILIENCE DESIGN PART???...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…

Empathy

When I talk about the many ways people are or behave, many designers and developers throw their hands up and 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 antithetical 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???

Fingers

Phones are literally not flat. Some OS, browser and app creators like to assume the whole top of the phone is flat glass, and edge gestures--dragging from or to the edge of the screen.

IMAGE FROM DECK?

Plenty of devices have a raised bezel to protect the screen, and many, many users put cases on as shown in Figure XX. What this means is that a lot of people cannot actually get to the edge of the screen. If they really press their finger they can get skin onto the edge, but that's not how touchscreens work. They sense 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.

Resilience

Resilience engineering is something used to keep big, reliable services like Google, Facebook, Etsy, Flickr, Yahoo, or Amazon online. At a deep engineering level they follow practices and procedures to assure their systems are not brittle, and avoid failure or fail gracefully and can be fixed easily.

Resilience is usually defined as the ability of a system to absorb disruptions without tipping over to a new kind of order. A building when exposed to too much lateral ground movement settles into a state of “pile of rubble on the ground” unless you design it to resist this disruption adequately.

We approach all design of technical systems from the engineering perspective, and assume we can codify the process, so predict failure points. But we can’t. Our systems are embedded in other technical systems, embedded into complex systems, like the user carrying it around, who may be subject to rain, and traffic delays, and calming a screaming baby while carrying the groceries.

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 for your websites, and resume your apps. 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 literally cannot. On one project I worked on, I did some quick math during a meeting as we added use cases to the workplan. If stopped everyone to demonstrate that creating use cases for all variations would take approximately the remaining life of the universe.

These are arbitrarily complex products, so we have to embrace the complexity and design differently, to avoid error and fail gracefully.

Resilient Design

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. 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.

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

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 answer I am talking about with resilient design.

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.

Designing touch interfaces for all the problem cases I outlined--carrying groceries, edge gestures--means understanding at a basic level what sort of problems will be encountered, and avoiding catastrophe. For touch interface design always:

# Space items out as much as you can. # Put catastrophic # If interference is at all likely, make it so there’s an unrecoverable condition. Email format controls, for example, should never be right next to the Send button. Send is unrecoverable. # Design to not annoy. F # Prioritize your inputs hierarchically, not like desktops or printed paper--top to bottom-- but by putting the key controls in the middle of the screen. REORDER LIST ABOVE TO BE IN SOME ORDER, rewrite...

More wrapup: DON'T ASK YOUR CLIENT IF ACCESSIBILITY IS PART OF THE FEATURESET, IT ALWAYS IS.

Whether tactical, as with edge gestures and icon placement, or more strategic with decisions about architecture to prevent errors, we should 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
• empathy in ux...
• resilience...

• robin if he said temporary disability... This? http://a11yproject.com/posts/myth-accessibility-is-blind-people/

• accessibility/disability numbers