An idea from Andreas Bulling that UX should see user attention as a finite and valuable resource, and only “spend” attention at certain points:
The “pervasive attentive user interfaces” imagined by Bulling might utilize what he calls “attention accounts.” This is basically a running balance of available user attention. If I were to focus for a few minutes on this chat box in the next tab over, the result would be an attention withdrawal. The system would then know that I now have less attention—defined here as the act of concentrating on discrete units of information while ignoring other information—to give and so would adjust itself accordingly.
“Instead of interrupting the user whenever new information becomes available,” he explains, “future interfaces could trade information importance with users’ current interruptibility level and time the delivery of information appropriately—for example for a period of low cognitive load, free attentional capacity, or even boredom.” (Source)
The idea is somewhat related to Calm Tech and Tea Kettle Tech.
Conversations are based on small almost imperceptible pauses that serve as markers for interruption. See Conversational Gapping