Examples

Principle No. 6

Affordance

The physical characteristics of a thing influence its function and use.

The form of a thing makes it better suited for some functions than others. For example, wheels afford rolling, and negatively afford being stationary.
The form of a thing makes it better suited for some interactions than others. For example, buttons afford pushing, and negatively afford pulling.
When affordances are good, things perform efficiently and are intuitive to use. When affordances are bad, things perform poorly and are hard to use.
Design things to afford proper use, and to negatively afford improper use. When affordances are correctly applied, it will seem inconceivable that a thing can function or be used otherwise.

The push action required to open the left door conflicts with the “pull” affordance of the handle. The sign is a poor fix because it will usually be read after people pull the handle. By replacing the handle with a flat plate, the conflict is eliminated and the sign becomes unnecessary. The “push” affordance of the plate eliminates the possibility of error or confusion.

Principle No. 40

Dunning-Kruger Effect

A tendency for unskilled people to overestimate their competence and performance.

Incompetent people lack the knowledge and experience to recognize their own incompetence, as well as the competence of others.
This creates a vicious cycle: An incompetent person can’t perceive their own incompetence because they are incompetent; and overcoming incompetence requires the ability to distinguish skill levels, which is an ability they lack.
Conversely, highly competent people tend to underestimate their abilities and performance, and overestimate the skills of others.
Combat the Dunning-Kruger effect by teaching the inexperienced how to discern competence from incompetence. Provide regular feedback and critiques to promote the development of self-assessment skills.

The least competent tend to be the most confident, and then the roller coaster ride of reality begins.

Principle No. 50

Fitts’ Law

The time required to touch a target is a function of the target size and the distance to the target.

Proposed by American psychologist Paul Fitts.
Used to model pointing to an object or computer screen using your finger or pointing device.
The law is predictive over a wide variety of conditions, devices, and people.
The primary implication of Fitts’ law is that close, large targets can be accessed more quickly and with fewer errors than distant, small targets.
Constraints can effectively increase target size. For example, a dropdown menu located at the top of a computer display effectively has infinite height because the screen edge stops the cursor.
Consider Fitts’ Law when designing controls and control layouts. Keep controls close and large when speed or accuracy is important.

The time and error rate involved in whacking a mole is a function of the distance between the whacker and the mole.

Principle No. 140

Veblen Effect

A tendency to find a product more desirable because it has a high price.

Proposed by the economist Thorstein Veblen.
In certain cases, higher prices increase demand, and lower prices decrease demand.
For example, the effect is most pronounced for items and services that signal status, such as art, jewelry, clothes, cars, fine wines, hotels, and luxury cruises.
High prices increase perceived quality, and low prices decrease perceived quality.
Consider the Veblen effect in marketing and pricing. Promote associations with high status people (e.g., celebrities). Employ strategies to discourage knockoffs, including legal protection, watermarking, and aggressive counter-advertising. Set prices high based on the intangible aspects of the offering.

Tesla Roadster

Electric cars are historically slow, ugly, and uncool. How to change this perception? Introduce a sexy electric car in limited numbers, associate it with people of status, and charge a premium. Once product perception makes the transformation from white elephant to white tiger, introduce lower-priced models. The Tesla Roadster: Veblen good.