THREE MODELS FOR USER INTERFACE DESIGN 

The 3 models for the user interface design are the implementation model, mental model &the manifest model.

The Implementation Model:

How the program is to be designed is covered in the Implementation model.

The Mental Model:

This model looks like the user's view. If the reasoning and logic is integrated in the manifest model it becomes an implementation model. However it would result in a bad interface. In Adobe Photoshop, to adjust the color, a sequence of small sample images with a various color balance is displayed. The user can click on the particular image to choose the specific color. As the user is thinking in terms of colors, it looks like the user's view. Therefore it follows the mental model. This is an illustration for the mental model.

The Manifest Model:

The way the designer selects to render the program is the manifest model. This model can be changed. If the logic is abandoned in rendering, then the manifest model will generate a good interface. This is because it follows the user's imagination.