When you interact with others, your communication and all that influences it—perceptions, thoughts, feelings, and emotions—are constantly in flux. This has several practical implications. First, no two interactions with the same person will ever be identical. For example, someone you once felt awkward around may become your closest confidant.

Second, no two moments within the same interaction will ever be identical. The complex combination of perceptions, thoughts, moods, and emotions that fuels our interpersonal communication choices is constantly changing. For instance, you meet your long-distance romantic partner at the airport, and for the first few minutes after reuniting you both feel joyous. But half an hour later, you suddenly find yourselves at a loss for things to talk about. As the minutes pass, the tension increases as you both silently ponder, “What happened?”