One of the considerations in interface design is that not only do you have to acknowledge that you are not the user, but that your users will all come from unique background experiences. During life our quest for knowledge takes us from zero at birth, and many strive for that unobtainable ‘all knowing’ status. Our experiences leave us somewhere in the middle at our ‘current’ knowledge point.
When we strive to do a new task that we have never performed before, that becomes our ‘target’ knowledge. Our goal to assist the user to get to their ‘target’ knowledge is to remove the gap between current, and target. Designers can use many techniques, but there are only 2 ways of moving a user from their current knowledge to their target knowledge, and that is either through training, or by moving the target closer to current by simplifying the design.
Often times when a user struggles with a task during User Testing, they will need a nudge in the right direction. Sometimes giving them a hint one time, will allow for them to accomplish the rest of the tasks (usually I remind them that left click, right click, and double click are all options). Usually the next time they are faced with the same challenge for which they received a nudge, they will glide past it without even giving it a second thought. I call this a “learn once, use many” situation — a pattern that is used consistently throughout the UI, a metaphor that makes sense. If the user does not hesitate during the next encounter, I will usually not suggest its removal.
The way to move the user from current knowledge to target knowledge by simplify the design is to do things like reducing the number of fields on a form, or stepping the user through the sections, or using dynamic displays so that the users actions determine their next steps. Requiring field validation informs the user immediately when they enter invalid information and makes it impossible for the user to proceed.
Another technique for simplification is to map out what we know about our users and their tasks starting with basic information and moving on to more complex concepts. You can use personas and scenarios to illustrate examples of levels of current knowledge starting points.
Jared Spool of UIE 18 discusses what he calls The Magic Elevator of Acquired Knowledge as a metaphor for a way to illustrate the Knowledge Gap and how it can be reduced.