The Consistency Principle
Lidwell et al tell us that consistency enable people to efficiently transfers knowledge to new contexts, learn things quickly and focus attention the relevant aspects of a task and that there are four kinds of consistent.
The first, aesthetic consistency is seen in the logo which uses consistent font, colour and graphic. This consistency of style an appearance enhance recognition communicates membership and sets emotional expectations. Whilst they use the Mercedes Benz logo this is applicable to Ferrari, IBM and the Kangaroo of Qantas (see figure 1).
The second, functional consistency enables people to use existing knowledge about how the design functions thereby improving usability and learnability. For example control symbols on tv control devices and music control devices have consistent symbols for increasing and decreasing volume. For examples the “power button” (see figure 2) on electrical products are almost identical and usually red in colour when on “standby mode” but when active turn green in colour. Thus functional consistency refers to consistency of meaning and action.
The third consistency illustrated by Lidwell et al is internal consistency which refers to consistency in the system eg signs within underground rail system are consistent with one another.
The fourth consistency illustrated by Lidwell et al is external consistency which refers to consistency with other elements in the environment eg hazards flashes in cars, consistent across all brands.
- Lidwell, W., Holden, K., & Butler, J. (2003). Aesthetic‐Usability Effect. In Universal Principles of Design (pp. 18‐19). Massachusetts: Rockport.
- Qantas Logo Image
- Power Button Image