Across languages and cultures, people’s natural speech involves brief, but sometimes annoying pauses that fill the air with sounds like ‘uh’ or ‘uhm’. But while these disruptions may sound like random nonsense, a new study suggests they can offer a rare glimpse into what’s going on in the brain when we speak. According to neuroscientists, we use uhs and uhms in specific situations when a relatively high linguistic effort is required.

Like, um, it’s all in the brain

Speech fillers are known as disfluencies and are often given a bad reputation, being associated with nervousness and trouble expressing one’s ideas. But although research suggests that anxiety significantly increases the frequency of all speech disturbances, such as the familiar ‘ah’, virtually all people use them, at least to a degree. Even people who use sign language to communicate sometimes wiggle their fingers.

According to one study, disfluencies pop up every 4.6 seconds, on average, among English speakers from the U.S. These tend to surface in certain situations, such as before difficult to pronounce words or when a new conversation topic arises, another study found.

These findings seem to be confirmed by a rather unusual study performed by neurologists at Wayne State University, led by Professor Eishi Asano. The researchers performed electrocorticography (ECoG) on three adolescents with drug-resistant focal epilepsy, during which a small incision is made in the skull and electrodes are placed directly on the exposed surface of the brain. While their brain activity was recorded with ECoG, each participant had to describe various complex scenes presented in photographs, such as a hippo bathing in a puddle during daytime.

Originally, the researchers wanted to see whether different regions of the brain were active when describing different concepts, such as what’s in the picture, where the action takes place, what is happening, and when. But as the participants fumbled their words, the researchers noticed something interesting in the patients’ brains.

When disfluencies were present, the neuroscientists noticed significant activation in the association cortex, a group of areas in the brain that is linked, among other things, with relatively difficult language tasks.

These brain scans suggest that uhs, uhms, and other disfluencies are behavioral marks that show people are scrambling their brains to find the next word because the association cortices are activated.

“Our preliminary results raise the hypothesis that filler utterance would often occur when large-scale networks across the association and visual cortex are engaged in cognitive processing, including lexical retrieval as well as verbal working memory and visual scene scanning,” the authors wrote in the journal Scientific Reports.

So, like, uhm, don’t worry if your speech has a moderate amount of filler words. Sometimes, it’s a good sign that the conversation is actually stimulating.