We can’t use non-verbal signals such as facial expressions, tone and volume of the voice, and body language when we text. That’s why we replace all this by text imitation: capital letters and exclamation marks when we are shouting or when we are angry or grammar mistakes made on purpose when we want to show that we are not interested or busy. A period is a signal that we are serious or that a conversation is over, as explained by Mark Liberman, a professor of linguistics. That’s why a person who uses a period at the end of a sentence seems angry to us.
