Principles of Interface Design
Perception ► Perceptions vary between the developer and the user. ► The user may not be aware of the fine details in a GUI, such as the importance of colour or the positioning of icons. ► Likewise the developer may not be fully aware of the users capabilities, wants or needs.
Colour ► The use of colour is extremely important in the design of GUIs. ► Microsoft Office uses grey as the predominant colour, blue for title bars and drop down menus. ► Many users feel this is boring, however if black and red were used it would soon become uncomfortable on the eye.
► Colours affect different people in different ways, some find yellow easier to read, others find it fuzzy. ► Users with dyslexia may be affected by colour in different ways, as would users who are colour blind ► GUIs with 3D effect are based on the Trichromatic system (the combination of the 3 colours that are basis of 3D vision: red, blue and green)
Luminance ► The three colours of the trichromatic system are detected by three different types of cells on the retina of the eye (receptors). ► These signals are opponent colour channels because they relay information about opposite colours. ► The theory states there is a hierarchy of luminance, red-green, yellow-blue, black- white, early colour parings cannot effectively display detail.
Why is yellow text on a white background difficult to read Where as blue on a white background is not.
Pop out effect This is used where there are a lot of symbols or imagery and one is required to stand out. This can be done by: ► Aligning differently ► Colouring differently ► Adjusting to a different shape. Preattentive Processing Theory
Pattern ► Microsoft uses a template for its dialog boxes. It provides consistency and evenness (symmetry) ► It aids he way the user relates to the interface, providing user friendliness, consistency and ease of use (connectedness). ► Consistency helps the user to feel comfortable with what happens next (save as – dialog box – file name – location) – Home button in the same place, links to websites underlined in blue, etc.
Gestalt Laws Gestalt laws have been formulated to describe our pattern perception and form rules for our designs: Proximity: we view things which are close together as a group. Continuity: smooth continuous lines are more easily interpreted than rapidly changing lines. Symmetry: we see symmetrical shapes easier than unsymmetrical shapes. Similarity: we see similar objects as a group, dissimilar objects tend to be viewed as individuals.
Positioning Positioning and layering are vital. If not parts of the GUI may appear behind the main screen and the user may not be able to access a full range of commands. Objects need to placed in a hierarchical system. If images are sitting behind or in front of other images then the entire interface will not be visible.