Hierarchy VS Usability in Mobile Design

Question

Taking into consideration the ease of access areas on a mobile device:

I am not sure how to determine/prioritize where to organize the main actions:

Hierarchy: Most important actions at the top

• Implications: might be on an area harder to reach

Usability: On the bottom 1/3 of the screen where the buttons are easier to reach.

• Implications: they loose importance on the overall layout.

For better understanding here is a mockup example of a Point of Sales app. The seller (user) will add products to the shopping list and then select the payment method. Here are the two approaches: (Actions inside the red rectangle are the main actions.)

Question Locate manin actions on a screen based on usability or hierarchy?

There might be other options/information that I might be missing so I would really appreciate other approaches, points of view based on experience or research.

ps: also appreciated Research regarding why search bars and other important actions are at the top of the screens regardless the ease to reach them, and if that has an impact on usability.

Thanks!

Answer 1

Just thought that I would try to point out some assumptions (which should be verified by testing in some way) that you may want to consider:

The ease of access image that you are showing is likely to be a single-hand use case for a left hand (not necessarily left-handed user) and probably for the thumb, but from experience there are many different ways that a person may hold and use a mobile device so I would try to see what the actual operating method and environment is. For instance, a POS app may also be used like a tablet sitting on a counter, in which case the ease of access areas could be quite different.

In terms of hierarchy, you need to define what most important actually means because there are at least two different interpretations here. The first is frequency of use, which means that items or actions most often used will be at the top because it is easiest to get to on a vertical scrolling view. However, you might find this could be modified by the purchase workflow, with the most often used feature at the bottom (such as checkout or accept payment) because it is the last step in the process so it doesn't need to be at the top.

In terms of usability, I think again you are basing the assessment on just the physical reach of the thumb if you are going by the diagram, when in fact this may not be the case. Also, it is important to consider the interaction or micro-interaction patterns as part of the usability analysis, as well as visual design styling that will help create a smoother and more fluent experience for the user.