Mental Models

Mental Models

1. Building a Mental Model

   • Babies do not have mental models, they will simply react instantly to the world.
     • If you are hungry, you cry. If you are tired you sleep and so on.
   • Over the years you instinctively build up an understanding of how the world works in the form of a mental model.
   • The predictive power of this model lets you very easily understand what is coming up next when an event happens.
     • Sticking your finger in boiling is not a good idea as your mental model tells you what will happen.
       • This does not mean that the world is a completely predictable place.
   • Your mental model of the world is not complete because you have not experienced every nuance of living.

2. Designing an interface

   • The HCI designer can take advantage of people's mental model of how interfaces should work. This allows the interface to be predictable and therefore easy to use.
   • Some interfaces can be difficult to work. You will have to use trial and error or follow instructions to make sense of the interface.
     • This does not make the interface bad, it just means that the user had no mental model in place.

3. Making an interface predictable

   • Most experienced computer users have a mental model of the functions of familiar icons and controls.
   • Functions on the toolbar are designed to give predictable results.
     • For example, Bold, Italics and Underline have appropriate buttons related to their functions.
   • With radio buttons it makes sense that only one can be chosen at a time. Like an old fashion radio, only one station can be played at a time.
   • The behaviour of the system itself should take account of the user mental model.
     • For instance, if they require to input text, it should be expected that text will wrap over lines.
     • Saving/opening files should use the standard File-Save/File-Open method, as well as any common keyboard shortcuts.

4. Benefits of conforming

   • Benefits of conforming
     • Makes the interface predictable
     • Easy to learn
     • Easy to use
     • Simple to guess where controls are likely to be
     • Transferable skills
   • Problems with not conforming
     • Difficult to learn quickly
     • Harder for the user to guess where things are
     • Mistakes more likely to happen