In a task-switching situation,the user must activate resources for the second task and inhibit resources for the first task. If theuser fails to do so efficiently, performance is reduced, sometimes dramatically.

If both tasks demandcontrolled processing, then the strategy in processing is split into two mechanisms: facilitationand inhibition.

The implementation of such a strategy requires attentional resources, which canlead to task interference when the demand exceeds the available capacity.

The third theory is information processing analysis theory. Ifat least one task can be carried out automatically, the other task can be carried out with little orno impact on performance (at an appropriate time–error trade-off point).