Thursday, December 16, 2010

Usability from a neuroscience perspective

There are many definitions to usability, I will not try to create one myself, but to explain how I see it.

Whenever users needs to do a specific task with a certain application, they are facing two problems:

  • What to do - this is defined by the user (or for the user by someone else)
  • How do I do it - this is defined by the application developer
In order to solve these problems, the user needs to allocate mental resources. Better usability results in less allocation of mental resources to deal with the second problem.

Basically, usability is about reducing the users' mental burden by providing good answer to the how problem, and thus allowing them to to concentrate on the what problem.

I've used the term "mental resources", so here's a short, not complete list of mental resources ordered by the cost of using them - from the cheapest to the most expensive:

  • Memory:
    • Mechanical - from climbing stairs without thinking about it to typing our thoughts without looking at the keyboard
    • Emotional  - what we feel about things
    • Intellectual - processes in solving problems that we already used and don't need to develop
  • Learning - the process in which we transform something that we don't understand to something that we do
  • Problem solving and creativity - the process in which we're getting from point A to point B,  without initially knowing the way (or even whether point B exists)

Just to illustrate how much energy our brain needs, it is enough to point that during sleep, one third of the body's needed energy is required by the brain. Now think how much energy the brain needs when you are active, receiving constant stimulation from the environment,  remembering  things, and also trying to be focused and do your job.

Thinking is hard and consumes a lot of energy, and we can expect users (as well as any other person) to try to reduce the thinking effort.
Therefore users don't:

  • Read manuals
  • Read all the info given within the application
  • Understand all the symbols in icons
  • Read messages that pop-up
Understanding that each and every call that we do in UI design, affects the price that the users pay in terms of mental resources allocation, is the first step towards having much better and usable applications, and this is what this post is all about.

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