Models and Theories in Human-Computer Interaction/Norman's Affordances - Visibility and the 7 Stages of Action

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There are 2 key items in Norman’s The Psychology of Everyday Things that I specifically want to speak to;

  • (1) make things visible
  • (2) use the 7 stages of action

Norman may not have adhered to the strictest definition of ‘affordance’ but his theory is profound and insightful in its simplicity. He basically ignores the concept that an affordance can be ‘invisible’ and stated that affordances must provide strong clues to the operation of things. Also, when affordances are taken advantage of, the user will know what to do just by looking. He extended his theory to state that the value of a well-designed object is that when it has such a rich set of affordances that users can do things with it that the designer never imagined.

One of the most important principles in the design of a system is visibility. This really resonates with me! The first step in system design should be to understand the need for visible management of the system. Users rarely take the time to read instructions and businesses today do not have the time to pull out the users manual each time they start a task. It is the responsibility of the system designer to make the operation clear, project a good image of the operation and to take advantage of other things people might be expected to know. This process starts by providing a good conceptual model and making things visible.

Because people form mental models thru experience, training and instruction the first step in the development process should be based on these mental models as you are forming the goal and forming the intention. This needs to be based on perceived actions and visible structure. Once this is complete, you can specify the action and execute the action. This should always be followed up with a transparent evaluation of the results. These are all steps defined by Norman in his seven stages of action: forming the goal, forming the intention, specifying an action, executing the action, perceiving the state of the world, interpreting the state of the world and evaluating the outcome.

I once saw an excellent example of the seven stages of action. I was at a conference where they were polling the audience response to the speaker. The polling device was a dial that was clearly label ‘hate it’ on the low end and clockwise from there ‘love it’ on the high end. This simple mechanism allowed the participants to twist the dial as they listened to the speaker. The system captured the audience response as the speaker spoke. The results gave a very clear graph of how the audience was responding emotionally to the speaker. The dial was a simple visual tool that was easy to use and participants clearly put their likes and dislikes into the poll with a very simple and natural twist of the dial.

Even with the best system design in the world, one item to keep in mind is the fact that these mental models need to be refreshed so they stay current. Evaluation must be an on-going process. I personally think the save button on computers is ridiculous. It is generally shaped like a ‘floppy disk’. No one under the age of 25 has ever seen a floppy disk. This visual image is not sustainable going forward and an alternative needs to be developed and deployed.

Norman suggests that we use the 7 stages of action as a design aid. It can help simplify a system design if you review each stage of action and question the design along the way. To do this he offers advice in the design process; tell what actions are possible, determine mapping from intention to physical movement, perform the action, evaluate whether the system is in the desired state, determine mapping from the system state to interpretation, tell what state the system is in.