The quesion of user expectations seems to be quite straightforward in the physical world. Any designer of physical world UI (e.g. architecture/ interior design/ vehicle interior/ furniture/ patient aids/ etc) can easily observe and test user expectations, because we have thousands of years experience with physical UIs and test participants are all around us, all the time.
Take this example with door handles:
Two of the pillars of good usability - visual consistency and visual hierarchy, can be properly designed only if we have reliable insight into user expectations.
What should be the requirements for visual consistency and visual hierarchy when it comes to door handles? In order to answer this question, we must ask first, what are users expectations regarding visual consistency and visual hierarchy when it comes to door handles?
Well, when it comes to visual hierarchy there is just one isolated case when it could possibly be relevant at all - when you have a second door lock on the same door, for extra security/ for different access levels - e.g. landlord and tenants. For the sake of brevity, let's skip this case, as it is a rare one, anyway.
When it comes to visual consistency, we can break it into the following parameters of physical world objects:
- size;
- shape;
- material
- colour;
- spatial position;
- type of mechanism.
Now let's think, if somebody changed door handles overnight, in our homes, would we have trouble using them:
- if size was changed >> I'd say not really, unless it was a significant change;
- if shape was changed >> I'd say not really, as long as the change was some artistic variation of the usual shape of a door handle; if it was a violation of the convention, I think, that'd be quite of a usability trouble;
- if material was changed >> might not even get noticed;
- if colour was changed >> might not even get noticed;
- if spatial position was changed >> e.g. put the door handle in the middle of the door, or half way above or below its usual position - quite heavy an issue!
- type of mechanism >> e.g. lever latch to a door knob >> serious issue, again.
(I am speaking about my personal UI expectations, of course and I am speaking hypothetically. If you have any difference here, please, share it in the comments.)
Figuring out user expectations in the physical world is no brainer, since we have abundant instances of the UI-s serving the same purpose and abundant respondent samples, which can be observed anywhere, at any time, without setting up expensive usability tests and experiments. Context is not that significant and easy to isolate when necessary. And in most cases, personal experience is representative of that of other users.
Now, compare that with virtual UIs, web sites in particular. When it comes to visual consistency or visual hierarchy, you'd hardly find guidelines explaining which visual parameters we should take into account, which ones do not matter and which ones matter only if changed to a significant degree. Actually, I have never stumled upon any UI guidelines or article on the topic, even considering such questions - they speak about visual consistency, as if you should keep all visual parameters the same, all the time.
While you'd witness heated debates in meetings, you'd be lucky to hear any backing research. It all boils down to designers trusting their personal preferences, their gut feelings (or/ and their overinflated egos). Where evidence is absent, magical phrases such as "it depends", "depends on context", "my experience", "Google are doing it this way", etc, act as substitute.
Therefore, my questions is, for the sake of discovering patterns in user expectations when in comes to visual consistency and visual hierarchy, have you resorted to seeking UI analogies with the physical world? If so, what have been your best practices? Was it a productive approach, altogether?
