The third allocation strategy is to allocate each function in a way that maximizes economicefficiency.

The second allocation strategy is assigning each function to the most capable agent, which canbe either a human or a machine.

Therefore, this automation strategy definesthe roles and responsibilities of users in terms of automation instead of the other way around.

First, byautomating everything that can be automated, the user is left with functions that, by definition, thedesigners find hard, expensive, or difficult to automate.

The first strategy is called maximum automation. Here, each task that can be automated is allo-cated to a machine.

The aim is to increase efficiency, reduce costs, or both.

Which system functions should beautomated, and to what extent should they be automated?

Task allocation is a central challenge in HCI and automation.

Independently of the chosen strategy, some tasks are to be done by the interactive system andsome by the user. The allocation of such tasks is called functional allocation.

In all cases, getting the right balance betweenautomation and human control is crucial.

In HCI, automation poses the foun-dational problem of task allocation: Who does which task or subtask—the system or the user?Moreover, how much should we automate?