Task Analysis and Modeling

The Task analysis and modeling can be applied to understand the tasks in which people presently perform when using a semi automated or manual approach and then map these into a same but not necessarily identical group of tasks which are implemented in the circumstance of the HCI. This can be accomplished through observation or through studying an existing specification of a computer- based solution and deriving a group of user tasks which will accommodate the user model the system perception and the design model.

Regardless of the whole approach to task analysis the human engineer must 1st classify and define tasks. One approach is stepwise elaboration. Example for suppose that a small software organization require to build a computer aided design system explicitly for interior designers. Through observing a designer at work the engineer notices that the interior design is comprised of a number of main activities: window covering selection fabric and material selection wall furniture layout and presentation to the customer, costing and shopping. Each and every of these main tasks can be elaborated into subtasks. Example for, furniture

layout can be refined into the following tasks that are given below:

(1) Draw floor plan based on room dimensions

(2) doors and place windows at appropriate locations

(3) use furniture sample to draw scaled furniture outlines on floor plan

(4) move furniture outline to get best placement

(5) label all furniture outline

(6) draw dimensions to show location

(7) draw perspective view for customer. A same approach could be used for each task and the other major tasks.

Subtasks one to seven can each be refined future. Subtasks one to six will be performed through performing actions and manipulation information with the user interface. On the other hand subtask seven can be performed automatically in software and will result in little straight user interaction. Design model of the interface should accommodate each of these tasks in a way which is consistent with the user model the profile of a typical interior designer and system perception what the interior designer expects from an automated system.

Another approach to task analysis takes an object-oriented point of view. The human engineer observes the physical objects which are used through the interior designer and the actions which are applied to each object. Example for interior the furniture template would be an object in this approach to task analysis the interior designer would pick the appropriate sample move it to a position on the floor plan trace the furniture outline and so 4th. The design model for the interface would not define implementation details for each of these actions but it would describe user tasks which accomplish the end result drawing furniture outline on the floor plan.

Once each task or action has been described interface design starts. The 1st steps in the interface design procedure can be accomplished using the following approach:

1.    Establish the motive and intentions for the task

2.    Map each motive intention to a sequence of specific actions

3.    Specify the action sequence s it will be executed at the interface level.

4.  Indicate the state of the system example for what does the interface look like at the time in which an actionist eh sequence is performed?
5.    Describe control mechanism example for the action and devices available to the user to alter the system state.

6.    Show how control mechanism affects the state of the system.

7.    Indicate how the user interprets the state of the system from information gives by the interface.