An exclamation point ( ! ) is used to end a sentence expressing strong emotion or commands (Stop!), and may be used to close questions that are meant to convey extreme emotion (What were you thinking!

Watch: What is an exclamation mark? An exclamation mark is used to show when something is surprising or forceful. It helps make the meaning of the sentence clear. If you want to shout, cry ...

While the study didn't look at exclamation points specifically, the general takeaway here seems to be that punctuation makes a big difference in how you come off. Using an exclamation point after ...