THUMB LIMITATIONS
Some apps force users to perform painful movements to reach a command without the use of their second hand. This is a design oversight for mobile apps in particular as well as responsive websites. The lack of ergonomically conscious user interfaces can lead to problems for both the user and the product's usability.
A history of one handed accessibility for the right hand thumb.
The graphics above are a great guide for where CTAs and repetitive interactions should take place on a phone. The green represents the area that falls within the range of comfort for the thumb. The orange areas are harder to reach but still accessible without significant discomfort. The red zones either hurt to access or are completely out of the thumb's range while holding it with one hand.
When the layout of an app's design causes undue stress in the hand to accomplish a common task, this can have huge effects on continued use of the product. If a user can't reach it, they may find the interaction laborious, potentially disrupting desired user flows and negatively effecting conversion rates. If a user feels pain in their hand from using an app, they might even feel motivated to leave a negative review in the App Store, further effecting growth of the product user base.
Distribution of the three most common holding positions.
The use of the app/website should be considered. For games, two handed use is often expected, but for something like a transportation app one hand may be more common. So when designing there are some questions that should be asked:
- Is the user likely to have both hands free? If not, then ensuring that both the primary and secondary CTAs are within reach of the thumb is probably a good idea.
- What if a mistake was made? Is the cancel/back option in the hard to reach top corner?
Apple was clearly aware of this issue when they introduced their larger screens with iPhone 6, but the lack of user adoption with Reachability is evidence that Apple failed at addressing this problem for most users.
VISUAL CONSIDERATIONS
Eyes develop their own habits that are tied to comfort. After long periods of time we develop mental models based off experiences interacting with many products. Our cultural and educational upbringings have also trained our brains in certain ways, such as looking and reading from left to right, top to bottom.
At this point in 2017, most of us expect the "Next" or "Submit" CTA to be a thick bar located along the bottom of the screen. Experimenting with placements of interactions that have become universal can create discomfort and annoyance for the user, resulting in reduced user satisfaction.
Eye tracking display of where users tend to look on their devices varying from smartphones to tablets.
Knowing these things about human expectations and habits can help us plan for where to put the main content on a page. This can also be applied to modules, pop ups or other things we really want the user's attention to focus on.
A particularly frustrating structure commonly in use is websites with a thick banner that remains at the top of the screen as the user scrolls down, constantly forcing their eyes to look towards the bottom two thirds of the screen where the content is. This goes against our natural inclination to keep our focus in the center to top region.
EYE-THUMB COORDINATION
Control of motor functions, hand dexterity and clarity of vision vary from person to person and are all factors that contribute to a user's ability to interact with a product as intended. Ensuring that interactions have enough space between themselves so that precision isn't required by the user is a great way to prevent user frustrations.
This diagram shows user accuracy in relation to screen placement.
The diagram above displays circles that's represent the varying accuracy users have in a particular area of the screen. The smaller the circle, the more accurate users tend to be. Users tend to be more precise in the center of the screen because the thumb is more relaxed. The larger circles in the corners reflect the difficulty in reaching these places--we must strain to reach these places and so our accuracy suffers as well. On top of that our vision is impeded by our own hands at times, also adding to our inaccuracy.
ALL TOGETHER NOW
Incorporating ergonomic principals into our designs is something we should always keep in mind. Comfort increases usability, decreases friction and allows us to enjoy the product experience more, increasing our likeliness to want to use the product again in the future.
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