As a species, humans don’t think hard about blinking. It’s just not the central drama of our days. However, a recent study found that blinks are important non-verbal communication — and that when we’re talking to someone, we subtly and subconsciously respond to the length of their blinks.
Previous research has found that people don’t blink at random in conversation, either. Though you blink subconsciously, you nevertheless tend to do it toward the end of a conversation partner’s “turn” in a chat. Researchers believe that it’s part of an array of gestures, like nodding, that you use to signal you understand what someone is telling you. Blinking is like nonverbal shorthand for “Got it!”
But are all blinks created equal?
To test this theory, they asked 35 people to converse with a digital avatar projected on a screen. This female figure would ask subjects open-ended questions — like “How was your weekend, what did you do?” — and then listen as they responded. She signaled her listening with nods paired with either long or short blinks. (When researchers observed organic human conversations, they found that nodding and blinking typically went hand in hand.)
Both of the avatar’s blinks lasted for less than a second; the short blink was 208 milliseconds, and the long blink was 607 milliseconds (translated to music, this would be a sixteenth note and an eighth note, respectively, played at around 60 beats per minute). That timing made them read as basically unremarkable; when asked about the avatar’s blinking afterward, subjects said they didn’t notice anything special about it. Nevertheless, the length of the avatar’s blinks had a measurable effect on conversations. Short blinks led to longer, more detailed answers; long blinks prompted subjects to respond much more briefly.
More broadly, this study shows that we’re always subconsciously interpreting each other’s body language. Even when we’re speaking, we’re “listening,” too — to our conversation partner’s gestures. And when a friend tells you someone “seemed to understand” or “seemed to be losing interest,” but can’t put their finger on exactly why, they may be talking about blinking without even knowing it.