Design Principles and Usability

Design principles and guidelines

According to Pop,P(2001,p.13 ) defines that design principles is ‘high level’ recommendations based on well established knowledge about human behavior.

Ryan(c. 2009) clarify that many of these design principles has been concerned in design of computer interfaces like Microsoft Windows and Mac operation system these guide lines will make program interfaces easier to use but some of these recommendations may not relevant to web applications.

According to Spring (2004) highlights that there are various set of design guidelines has been introduced by various people.

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Table 1

But mainly principles and rules which are introduced by Shneiderman and Norman are popular and used in practice widely.

Ben Shneiderman

University of Maryland (2009) states that Ben Sheinerman is a professor in the department of computer science and the founder of the Human computer interaction laboratory in university of Maryland.

Also according to University of Maryland (2009) Dr.Shendierman is a author for many research papers in human computer interaction.

8 Golden rules of Ben Shneiderman

University of Washington(2009) defines that there are 8 rules proposed by Shneiderman and most of the rules are applicable to most of the interactive systems including web applications and guiding this rules the usability can be improved in software applications..

1. Strive for consistency
2. Enable frequent users to use shortcuts
3. Offer informative feedback
4. Design dialogs to yield closure
5. Offer error prevention and simple error handling
6. Permit easy reversal of actions
7. Support internal locus of control
8. Reduce short-term memory load

Strive for consistency

According to Shniederman(1998) as he highlighted that strive for consistency means consistent sequences of actions should be required in similar scenarios and use of identical terminology should be used in message boxes , forms and windows.

As described in Beckert & Beuster (2006,p. 22) we will take a text based e-mail application as an example for consistency.

Screen 1

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Figure 2 - Idle screen of the mailSource :Beckert&Beuster (2006,p. 22)

Screen 1

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Figure 3 - Screen 2 Source :Beckert & Beuster (2006,p. 22)

As above figures the menu is the bottom of the screen is constant for every screen in the application.

By consistency the interface users can easily understand the elements in the application

The following figure shows Microsoft office 2007 ribbon bar asan example for consistency .All the tools can be accessed as tabs.

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Figure 4 - Ribbon bar in Microsoft Office(Source: Microsoft Office)

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Figure 5 - consistency in Microsoft windows applications(Source: Microsoft Windows)

The above figure shows some windows of software applications the menu bar, toolbar, can be clarified as consist objects so user can easily identify.

Enable shortcuts for frequent users

As Pop, P (2001, p.22) defines shortcuts may advantage frequent users to do their tasks easily .shortcuts can be implemented in several ways like,

- Keyboard shortcuts
- Special menus
- Special Keys and icons
- Macros

Especially keyboard shortcuts and menus are frequently used in most of the applications and macros are pre recoded instructions which can be used instantly.

According to Microsoft Corporation(2002) ‘Official Guidelines for User Interface Developers and Designers ’ p.76 highlight there are many shortcuts are used in Microsoft Windows graphical user interface, like double-clicking with the primary mouse button is a shortcut for the operation of an object.

Keyboard Shortcuts

Also as Microsoft Corporation (2002) ‘Official Guidelines for User Interface Developers and Designers’ p.82 describes there are many keyboard shortcut techniques are used, for example to get help the default key is the F1 key and to close a windows the shortcut key combination is ALT + F4.Also custom software application may have customized keyboard shortcuts in use .

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Figure 6 - Keyboard Shortcuts(Source: Microsoft Windows)

Buttons and Menus

According to Microsoft(2009) in Microsoft corporation have introduced new concepts on Windows 7 taskbar which will provide quick access to programs and quick access to frequent tasks .

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Figure 7 - Taskbar in Windows 7(Source: Microsoft Windows)

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Figure 8 - Shortcut menu associated with the Task buttons(Source: Microsoft Windows)

As figure above shows task buttons provide shortcuts to frequently used programs and the newly introduced the shortcut menu which is associated with taskbar provides access more specifically. And these shortcuts are provided automatically as the frequent of use or user can customize the shortcuts.

Macros

Also in 90’s macros was a popular way of doing tasks easily .Pre-configured set of tasks will run when user requested or these tasks can be customized or generated by the user .but in modern days macros are not recommended to use because macro scripts have a high vulnerability of spreading viruses and spyware .

Special keys

The windows key is a special key ([illustration not visible in this excerpt]) which available in most of the keyboards which lead to shortcuts that can be used in Microsoft windows.