Module 3 Week 10

Answer 1:

The principle of consistency is that procedures and systems are easier to use and learn when their functions are expressed in familiar and similar ways to what we already know. If things are consistent the prior knowledge from another product means that things are more familiar and easy to do. There are four different types of consistency that we can see in design. They are Aesthetic, External, Functional, and Internal.

–       Aesthetic consistency is where something has the same appearance and style to it. This makes things instantly recognisable and draws people to understand it. For example the golden arches of the MacDonald’s logo are associated with fast food, in particular burgers and fries.

–       External Consistency refers to design elements that are common in all different environments. That way people are introduced to a different environment they can navigate their way around.

–       Functional consistency. This is all about actions and controls. Functional consistency is very important when we go to use things we may not be sure about. In a car all the pedals are kept in a certain order. Working left to right it is always, clutch, brake, accelerator. This means when people get into a new car the know how to use the pedals in it. Image in the pedals changed with each car?

–       Internal consistency refers to designs being the same in a particular area or system.

It is important to keep things consistent because they make peoples lives more complicated and generate confusion.

“inconsistencies force people to spend extra time trying to figure out how to navigate, or where to find the answers to questions they have.” Skaalid, B. (1999).

When things are designed it is important that there is consistency between the predecessor and the successor.  It makes for a smoother transition between the two. People should be more appreciative of consistency because we would be lost with out it.



Answer 2:

You can see the principles of consistency in everyday life. Here are three examples.

  1. The buttons on an MP3 Player: Whether you have an ipod or another portable MP3 player the symbols on the buttons do the same thing. The play symbol is the same, so are the pause, fast-forward, and rewind buttons as well. By keeping the buttons the same it means that people do not have to figure out how to use on portable music player form the next. This is a type of functional consistency.
  2. A Ferrari: It is one of the most recognised cars names on the planet, Ferrari. It also has a well know logo, the prancing horse. When people see the Ferrari logo they think of a high performance Italian sports car. Since that is all Ferrari has ever made the brand identiy has stayed consistent. This is a type of aesthetic consistency.
  3. Traffic lights: As the old children’s safety song goes, “stop says the red light, go says the green, wait says the orange light sitting in between”. People can instantly recognise them and know exactly what is means. If they had different coloured traffic lights in different countries it would create a lot of confusion amongst tourists.

This is a type of functional consistency.





Ulrich, K., Eppinger, S. (1995) Product Design and Development. New Yorok: McGraw Hill


Zuschlag, M. (2010, July 19) Achieving and Balancing Consistency in User Interface Design. Retrieved from:


Skaalid, B. (1999) Consistency. Retrieved from:


Cushman, W, (1991) Human Factors is Product Design. Amsterdam: Elsevier


Lidwell, W., Holden, K., & Butler, J. (2003). Aesthetic‐Usability Effect. In Universal Principles of

Design (pp. 46). Massachusetts: Rockport.


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