Recently, I wrote about intriguing new research from Northeastern behavioral psychologist David Lewkowicz and his collaborators, who found that infants learning two languages do more lip-reading than infants learning one language. This research builds on a previous study by the same research team, which found that babies who are first beginning to babble start to shift their attention to the mouth of the person speaking and away from their eyes.

But Lewkowicz says lip-reading is far from exclusive to babies—adults are doing it all the time, probably without even thinking about it.

He explained that in many social situations, people are not only hearing each other speak but are also seeing each other speak. Basically, it boils down to taking advantage of the available multisensory information you need to understand the speech—just like the babies he’s observed in his studies.

“All of us engage in lip-reading, whether we know it or not,” Lewkowicz explained. “If you go to a restaurant or bar where it is really noisy and you’re trying to have a conversation with someone across the table, you do quite a lot of lip-reading to help boost the signal, in essence. It help makes the information much more salient.”

In fact, Lewkowicz and some of his other collaborators have conducted a separate study with English-speaking adults who were asked to watch two videos: one with someone speaking English, the other with someone speaking Icelandic. After viewing the videos, the adults were asked what they thought was being said in the clips. It turns out the adults did more lip-reading in the unfamiliar language, the researchers found.

“We do this all the time,” Lewkowicz said. “If the information we’re hearing is unfamiliar to us, we tend to lip-read as well.”