Interface Design Models

Four types of various models come into play when a human computer interfaces is to be designed. The software engineer builds a design model and a human engineer   establishes a user model the end user establish a mental image which is often called the user's model or the system perception and the implementers of the system build a system image. Sadly these models may differ significantly. The function of interface designer is to reconcile these derive and differences a consistent representation of the interface.

The design model of the entire system incorporates interface procedural representations and data architectural of the software. The needs specification may establish certain constraints that help to describe the user of the system but the interface design is often only incidental to the design model.

The user model depicts the profile of end users of the system. To establish an effectual user interface all design should begin with an understanding of the intended user including profile of their age, physical abilities, sex, education, cultural or ethnic background motivation motive and personality additionally users can be categories as:

• Novices --no syntactic knowledge of the little and system semantic knowledge of the application or computer usage in common;

• The Knowledgeable intermittent users reasonable semantic knowledge of the application but moderately low recall of syntactic information necessary to use the interface and

•The Knowledgeable frequent user’s good syntactic and semantic knowledge which often leads to the power-user syndrome which is individuals who look of abbreviated and shortcuts modes of interaction.

The system observation is the image of the system in which an end user carries in his or her head. Example for if the user of a particular word processor were asked to define its operation the system perception would guide the response. Accuracy of the description will depend upon the user's profile example for novices would give a sketchy response at best and overall familiarity with software in the application domain. The user who understands word processors fully but has only worked with the exact work processor once might actually be able to gives a more complete description of its function than the novice who has spent weeks trying to learn the system.

The system image couples the outward manifestation of the computer based system the feel and look of the interface with all supporting information manuals, books, video tapes which describe system semantics and syntax. When the system image and the system image and the system perception are coincident users commonly feel comfortable with the software and use it efficiently. To complete this melding of the models the design model must have been establish to accommodate the information contained in the user model ant he system image must correctly reflect semantic and syntactic information about the interface. The interrelationship among the models is describe if Figure. The models define in this section are abstractions of what the user is doing or thinks he is doing or what somebody else thinks he ought to be doing when he uses an interactive style In essence these models enable the interface designer to satisfy a main part of the most important principle of user interface design: Know the user and know the tasks.