Eye contact is one of the earliest non-verbal communication tools that humans develop. It's how we show respect and interest, it helps us persuade people to do what we want, and the lack of it can quickly communicate if we're lying or if we dislike someone. "Eye contact provides some of the strongest information during a social interaction," James Wirth, a social psychologist at Ohio State University at Newark, told Scientific American. But getting eye contact right is tricky, and more isn't necessarily better. In a study published in Royal Academy Open Science, researchers found the participants liked eye contact best when it was 3.2 seconds. Any longer, and a gaze quickly goes from courteous to creepy.
Except — and this is where it gets even more tricky — if you're perceived as generally trustworthy and non-threatening. In that case, people are ok if you hold their gaze a little longer. "Gaze conveys that you are an object of interest, and interest is linked to intention," psychologist Alan Johnston, coauthor of the Royal Academy study, told Scientific American. Translation: If you're perceived as threatening — even if you have only the best intentions — it might be assumed you're up to no good.