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.
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.
