Blink Rate
One of the things that most people seldom consider is how frequently they blink. Since it's an automatic behavior, we are oblivious to how frequently we engage in it. The average adult blinks 15 to 20 times each minute, in case you were wondering.
Your blink rate will rise in a tense setting. This might suggest dishonesty, but it doesn't mean it always does. It could also be a sign of tension and discomfort in a circumstance. Having said that, if someone's blink rate suddenly increases while they are speaking, such during a speech or a courtroom witness, that could be a symptom of deceit.
Navarro notes that Nixon's blink rate increased from 12 times per minute to over 70 times when he was speaking and not necessarily being truthful. Check watch Bill Clinton while he was testifying in court; he was blinking more than 100 times per minute, which is a telltale sign of someone who is under stress.
Automobile salespeople and other professions who want to exert pressure on others receive instruction on how to spot blink rates. They'll keep an eye on your eyes to judge when and how to apply extra pressure to seal the deal. Therefore, be mindful of how often you blink and attempt to regulate it if you're going into a high-stress situation and want to appear that you're calm and collected.