Mental|Conceptual|System Models in UX

On my last ‘IxD for Developers’ talk at Hacker Dojo, I mainly emphasized on the importance of understanding  and differentiating  these models. Essentially, human beings are very different from one another. For this reason, we simply should not design for one type of user and should also not deny the fact that we all think/interact differently. To illustrate, engineers should not think like engineers when developing web or mobile apps. For the most part, in this talk, I tried to raise awareness in terms of designing interfaces that corresponded to user mental models, through better design of conceptual model.

A Summary of Definitions

  • Mental Model – think USER – the model that users have of themselves and of the outside world, formed through interactions, experiences, and instructions, and formed by user’s interpretation of a devise perceived action and its visible parts and structure
  • Conceptual Model – think INTERFACE – the actual model given to the user through the system interface, gives user the ability to mentally stimulate the operation of a system
  • System Model – think APP/DEVISE – how the system works inside, this part is like a Black Box to the user

In order to figure out an app or a devise, users gather several cues from the interface (the conceptual model):

  1. Affordances
  2. Constraints
  3. Mappings

In addition, users first try to mentally stimulate the object operation in their mind! So, imagine if your interface does not give all the clues needed for the user to (mentally) figure out how the device works. Your user is already confused, if not intimidated.

The Convergence Bicycle

This famous bicycle, mentioned by Donald Norman and drawn by Jacques Carelman, illustrates this point excellently. Although this devise is not ‘real’, you are most probably able to mentally stimulate its operation in your mind PLUS you are able to determine that this devise would probably not work. You did ALL that in your head without even touching or trying out the devise.

This illustrates a perfect conceptual model, as it communicates affordances, constraints, and mappings of the devise just through a drawing. And, for this reason, the outcome is a perfect conceptual model where the user is able to immediately tell how this machine is supposed to operate.

Some Fundamental Design Principles

  1. Provide obvious conceptual models
  2. Make things visible (and on the surface)
  3. Make users ‘see’ how things work
To Sum Up
  • Users are NOT interested in System models – they don’t want to know how things work INSIDE
  • System models have too much irrelevant information for the user
  • Users are only interested in Conceptual models because that is what they see and that is what will give them clues as to how the app works
  • Engineers do have control over the design and over the Conceptual model.  So USE IT!
  • Use affordances, constraints, and mappings to give clues to the users
  • If you think of these when designing your work, you will have happy users, which will increase the likelihood of them coming back to your app
Happy Coding and Designing!
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