Wednesday, January 11, 2017

Design Inconsistency

Consistency makes life easy.  Consistency makes sense.  Consistency in design reduces learning curve and eliminates confusion.  We subconsciously expect consistency and harmony around us.

Consistency has always been important in design of everyday things.  It is especially important when it comes to human machine interfaces.  Consistency makes everything seem normal and we feel at ease as we can operate in auto-pilot.  Imagine if the location of the accelerator and brake pedals were switched based on the brand of the car.  Every time you rent a car, you need to retrain your brain to this new interface.  This inconsistency is not only frustrating but can also be dangerous.  I remember a friend getting into a serious accident while riding another friend's bike in which the brake and gear levers were reversed (non-standard).  It was part of the design of the bike but in critical situations, the brain goes into auto mode and just does what it has always been doing.  He ended up frantically pressing the gear lever instead of hitting the brakes.

Another example is the riser of a staircase.  The designer can pick any height for the riser, BUT, it has to be consistent across the whole staircase.  Once a user starts climbing the stairs, the human mind programs itself to the height of the riser and we go into autopilot.  The user no longer has to look at the steps in order to continue.  The moment a riser is different (either shorter or higher), the user is guaranteed to trip.  Inconsistency is dangerous here.

We take notice when things are inconsistent.  Because inconsistency confuses us and throws us off.  It also frustrates us.  Here is an example I noticed recently at a Sheraton hotel in Vancouver.



During all my travel, I have always noticed that the elevator design is very consistent (but for some special cases like this) so as to provide the user with a familiar feel.  The 'door close' button is always on the right hand side and the 'door open' button is on the left hand side (Whether the door close button is a placebo button or if it actually works is a topic for another blog.  Let's stick to the design topic for now).  Once you hit the floor button, you subconsciously reach for the button on the right side to close the door.  I did exactly that and the door kept reopening.  I was distracted by my phone and did not notice why this was happening until, out of frustration, I 'looked' at the button to discover that it was reversed and I was hitting the 'door open' button.  Duh.

This case was not a 'designed inconsistency'.  It was an 'inconsistent inconsistency' because the other three elevators were all consistent and standard.

Inconsistency can be refreshing in some cases and can be an advantage.  An example is a web site (or a mobile app) design that is not consistent and does not follow the norms of design will always stand apart and draw the user's attention.  And, user attention is what everyone is craving for.  Again, the inconsistency should be subtle and not all over the place.  If it is extensive, it tends to drive the user away.

It is OK to be inconsistent when you want to draw attention, when you want to surprise (pleasantly) the user or when it is dictated by the design.  Designers have to make a conscious choice when to apply inconsistency to their design and what it would mean.  A thorough analysis should be undertaken before introducing inconsistency.  

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