According to researchers from Binghamton University, texts that terminate in a period are thought to be less sincere than messages that end without any punctuation at all. On the flip side, users believe texts ending in an exclamation point are more heartfelt and profound.
“Texting is lacking many of the social cues used in actual face-to-face conversations,” says research leader Celia Klin. “When speaking, people easily convey social and emotional information with eye gaze, facial expressions, tone of voice, pauses, etc. People obviously can’t use these mechanisms when they are texting. Thus, it makes sense that texters rely on what they have available to them: emoticons, deliberate misspellings that mimic speech sounds, and according to our data, punctuation.” (The Guardian)