However, it can be used as a non-manual marker to emphasize or modify the meaning of a sign. Here are some examples:
* Thinking: If you're signing about something you're trying to figure out, rubbing your chin can indicate you're thinking about it.
* Hesitation: If you're unsure about something, rubbing your chin can signal that you're hesitant or unsure.
* Doubt: If you're expressing doubt, rubbing your chin can add emphasis to your sign.
It's important to remember that the meaning of any non-manual marker is dependent on the context and the other signs being used.