Having worked in a product-centric domain for close to ten years, I had always heard the book, The Design of Everyday Things being mentioned with great reverence. Donald Norman, who is an academic and an authority in the field of cognitive science, design, and usability engineering, and the founder/consultant of Neilson Norman group is the author of The Design of Everyday Things.

When I came to know from Dan Olsen about an available course on the book being offered for free by the legend himself, I jumped on to the opportunity. The course is based only on Chapter 1 and Chapter 2 of Design of Everyday Things. Though it is not prescribed reading for the course, I would recommend to read it before the course.

Here’s what I learned from the course.

The course introduced me to 6 design principles:

  • Affordances
  • Signifiers
  • Conceptual Models
  • System Image
  • Discoverability
  • Feedback

Affordances:

An affordance is a desirable property of a user interface – software which naturally leads people to take the correct steps to accomplish their goals. The common psychological term for this is stimulus-response compatibility.
Affordance provides strong clues for the operation of things. For example in doors, plates are for pushing, knobs are for turning, slots are for inserting things.
When affordances are taken advantage of, the user knows what to do just by looking: no picture, label, or instruction is required. Complex things may require explanation, simple things do not.

affordance[1]

A chair affords (“is for”) support, and therefore affords sitting. A chair can also be carried.

Signifiers

When a product signifies that you can do something somewhere.

Conceptual Models:

It is an explanation in a highly simplified way of how something works. According to Don Norman, the conceptual model of a device is formed “by interpreting its perceived actions and its visible structure.” A short lesson on conceptual models point out that good design is also an act of communication between designer and the user, except that all communication has to come about by the appearance of the device itself. The device must explain itself.

A good conceptual model allows us to predict the effects of our actions.

When the designers fail to provide a conceptual model, we will be forced to make up our own, and the ones we make up are apt to be wrong.

Discoverability

All operations can be discovered by systematic exploration

System Image

The visible part of the device is called a system image. When the system image is incoherent or inappropriate, then the user cannot use the device.

 

mental-model[1]

User acquires all knowledge of the system through the system image.

Feedback

In design, it is important to show the effect of an action. Without feedback, one is often wondering whether anything has happened. Maybe the button wasn’t pushed hard enough; maybe the machine has stopped working; may be it is doing the wrong thing. Feedback is critical.

gulfofdiscoverability

The Seven Questions

The seven questions a designer must ask itself after a design.

Goal Question:

  • What do I want to accomplish? or What is my goal?

The Gulf of Execution is about discovery, so when crossing this gulf, users ask:

  • What are my alternatives?
  • What can I do now?
  • How do I do it?

The Gulf of Evaluation is about feedback, so when crossing this gulf, users ask:

  • What happened?
  • What does it mean?
  • Is this OK? Have I accomplished my goal?

None of these question applies to the World — the questions are about the product and the person’s goals for the product.