Wednesday, September 19, 2012

The Gulf of Execution and The Gulf of Evaluation

The Gulf of Execution
Primary question of users when meeting UI-s:  How do I do what I want to do ?

The Gulf of Evaluation 
Second question: What happened.


Can the user do what they would like to?
What representations are used for communication?

Solution what many UIs come across : Direct manipulation user interfaces


  • Immediate feedback on actions
  • Continuous representation of objects
  • Leverage metaphor  - we are more and more familiar with digital environment and we don´t need so many real world metaphors to understand an user interface. 



Good design reduces gulfs.

How easily can we:

  • Determine a function of the device?
  • Tell what actions are possible
  • Determine mapping from intention to physical movement
  • Perform an action?
  • Tell if system is in desired state?
  • Determine mapping from system state to interpretation?
  • Tell what state the system is in?

One strategy is really effective - Mental models.

Mental model in users head does not do what real life is really like.

There are many kinds of mental models:

  • My own behavior
  • Someone else´s behavior
  • A software application
  • .. or any information process that´s mediated


Metaphores: Learning Mental Models
"A text processor is a typewriter"
Mental models are inconsistent in time

Users and designers communicate through their mental model

Designer´s model = mental / conceptual model of the system.
User´s model = mental model developed through interaction with the system
Designer expects user´s model to be the same as the designer´s model. But often it isn´t!

Conceptual Model Mismatch
Mismatch between designer´s and user´s conceptual models lead to: slow performance, errors, frustration. You see this by walking around and noticing notes on devices etc where people write what to do or how to do smth.

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