I submit that it would be very nice to have a method other than verbal interruption that explicitly communicates to someone that you want them to stop talking. (Possibly an array of methods, depending on why you want them to stop.)
Hand raising serves this purpose pretty well. People tend to think of it only for when an audience member wishes to interrupt a presenter, and not for conversations between peers, but it seems suitable for peer conversations too..
Putting your hand out with an index finger raised also works pretty well, and might be less socially surprising. You can also vary the details to send different messages, with “arm out and index finger pointing just above the person’s head” being “stop talking right now!”
Hand raising serves this purpose pretty well. People tend to think of it only for when an audience member wishes to interrupt a presenter, and not for conversations between peers, but it seems suitable for peer conversations too..
Putting your hand out with an index finger raised also works pretty well, and might be less socially surprising. You can also vary the details to send different messages, with “arm out and index finger pointing just above the person’s head” being “stop talking right now!”