In general activity in the DFN decreases when a person is engaged in a task; the more demanding the task, the more the decrease. The attention and salience networks do the opposite. A classic experiment in this case would be to contrast BOLD signal in an fMRI experiment between easy and hard blocks, or between active periods and rest periods. The general observation about the anti-correlation of the DFN and task-activated networks is a very robust result, seen over and over again.