Distribution of Tasks (Division of Labor)

Why Pay Attention to Distribution of Tasks? | A Simple Rule | Restructure the Task | The Fewer Steps, the Better

When you design an application, you automatically distribute the steps that are needed to execute a task or to attain a goal between the computer and the user. This becomes particularly evident when you use a method such as Essential Modeling. Here you list the user's tasks or intentions in one column and the system's tasks in a second column. You can easily evaluate the user's workload and the system's workload.

Example: Getting Cash – Essential Use Case *)

User Intention

System Responsibility

Step 1: identify self  

 

Step 2: verify identity

Step 3: offer choices

Step4: choose

 

Step 5: dispense cash

Step 6: take cash

 

See also Who Does the Work? for more information and examples on this topic.

 

Why Pay Attention to Distribution of Tasks?

Usually, a computer system running an application is interactive. The system and the user communicate in order to a attain a goal or to fulfill a task.

With respect to distribution of tasks, the most important aspect of this communication is that the users have to provide data that the system needs for processing the task. This may mean more or less work for the user. This depends, among others, on:

  • How much data the users must enter
  • How often users must enter data
  • Whether users have to calculate or otherwise provide intermediate results
  • Whether users have to check intermediate and / or final results

Heavy workload for users may result in strain and, possibly, a lot of errors.

 

A Simple Rule

As a simple rule, let the computer do as much of the work as possible.

For example, do not prompt the user for information that the application already knows or can get otherwise. Also, do not let the user perform steps that the application can do for him or her.

 

Restructure the Task

Sometimes it may be helpful to restructure a task in order to simplify the interaction and to enable the system to take over a larger share of the work load.

 

The Fewer Steps, the Better

Remember, the less steps users have to perform, the fewer errors they can make, and the faster they get their job done!

Note, however, that there is no rule without exception. Often, users prefer to use simple commands that require repeated keystrokes to more powerful and complex commands that require just one or a few keystrokes. User behavior typically depends on the frequency of the actions. For rarely used actions, users find it easier to learn fewer commands and to use just a "handful" of simple commands that require more physical actions.

 

*) Example taken from Larry L. Constantine & Lucy A. D. Lockwood (1999), Software for Use. Reading, MA: Addison-Wesley.

 

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Source:  Simplifying for Usability