Thursday, January 03, 2008

The application of model matching principle in user interface design - Part 1

Examples and discussion of conceptual models ...

"The following picture shows a dustbin on a street in Beijing. (below)

It is clear that the dustbin consists of two containers: one in blue and one in yellow. The labels on the dustbin indicate that the blue one is used for materials that can be recycled, while the yellow one is for materials that can not be recycled. The problem is, however, how will people know what are the materials that can be recycled? If you ask the people around you, you will find that even some PhDs can’t answer it correctly.

2. Conceptual Model, Implementation Model and System Model

In order to see why the above dustbin’s design fails, let’s first look at three models and their relationships: conceptual model, implementation model and system model.

These three models are initially discussed by Donald A. Norman in his famous book The Design of Everyday Things. The conceptual model refers to people’s knowledge about a product and its behavior before using it. It can come from their past experience when using similar products, or their expectations of the product when using it for a specific purpose. The implementation model is about the internal structure and the working principle of a product. It is well understood by the product designer. The system model refers to people’s acquired knowledge about how to use a product after seeing or using it.

It can be seen from the above definition that elements in the conceptual model belong to the problem domain or task domain, while the implementation model is within technical solution domain. The conceptual model, as it belongs to the problem domain, is very hard to be altered by product designers. On the other hand, due to technology limitations, the implementation model will not vary greatly within a relatively short period of time. Only the system model has the greatest flexibility and can be easily manipulated by designers. Its position is always somewhere between the implementation model and the conceptual model. The closer it gets to the conceptual model, the less people need to learn how to use it. In another word, the product will be very easy to use because it is very close to the user’s expectation. On the contrary, if the system model is closer to the implementation model, users have to transform their familiar concepts in the problem domain into those technical jargons displayed on the product UI. From a psychological point of view, this transformation is an additional cognitive task that causes people feel the product difficult to use.

Now look at the dustbin example mentioned at the beginning. To correctly using it, a very important part of the conceptual model is about how people classify the garbage that they are going to throw. Most people only know if they are food, furniture, appliance or any other types of things. In the implementation model, however, the most important concept is about whether a material can be recycled or not. This is because the garbage needs to be processed in different ways, depending on whether it can be recycled or not. The system model, which is the dustbin labeled with “recycling” and “unrecycling”, is nearly the same as the implementation model, thus greatly deviating from people’s conceptual model. In order to use the dustbin correctly, people need to know whether the garbage can be recycled or not. However, the truth is that most people don't have this knowledge. So the result is that they will very likely throw their garbage into the wrong dustbin."    (Continued via uiGarden)    [Usability Resources]

Dust Bin Ergonomics - Usability, User Interface Design

Dust Bin Ergonomics


Blogger beracahvalley said...

Yeah true, the problem is most people may not know or even if they know cant be border. That is the problem with it.

The challenge is to raise the issue of global warming and how serious it will affect all of us perhaps.

6:20 AM  

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