We always thought everyone heard a voice in their heads, but we were wrong

Only in recent years have scientists discovered that not everyone has the sense of an inner voice—and a new study sheds some light on how living without an internal monologue affects the way language is processed in the brain.

This latest study, from researchers at the University of Copenhagen in Denmark and the University of Wisconsin-Madison in the US, also proposes a new name for the condition where there is no inner speech: anendophasia.

This is similar to (if not the same as) anauralia, a term researchers coined in 2021 for people who have no inner voice and cannot imagine sounds, such as a musical tune or a siren.

Focusing on inner voices in this study, the team recruited 93 volunteers, half of whom said they had low levels of inner speech, while the other half reported having a very talkative internal monologue. These participants tried a series of tasks, including one that required them to remember the order of words in a series, and another that required linking rhyming words together.

“It’s a task that will be difficult for anyone, but our hypothesis was that it might be even more difficult if you didn’t have an inner voice, because you have to repeat the words to yourself in your head to remember them.” says linguist Johanne Nedergård, from the University of Copenhagen.

“And this hypothesis turned out to be true.”

The volunteers who reported hearing inner voices in everyday life performed significantly better in the tasks than those without inner monologues: Inner speakers remembered more words correctly and matched rhyming words faster. The researchers think this is possible evidence that inner voices help people process words.

It is interesting to note that the performance differences disappeared when the volunteers spoke out loud in an attempt to solve the problems they were given. It may be that using an audible voice is just as effective as using an inner voice in these situations.

On two other tasks, including multitasking and distinguishing between different images, there was no difference in performance. The researchers take this as a sign that the way inner speech affects our behavior depends on what we do.

“Maybe people who don’t have an inner voice have just learned to use other strategies,” says Nedergård. “For example, some said they tapped their index finger when performing one type of task and their middle finger when it was another type of task.”

The researchers want to emphasize that the differences found do not cause delays that you would notice in a normal conversation. We’re still in the very early stages when it comes to figuring out how anendophasia can affect someone – and also anauralia.

Early findings from research at the University of Auckland suggest that people with ‘quiet minds’ remember verbal information in similar ways those who experience typical auditory images.

But there may be differences that we don’t know about yet. One area the team believes is worth further research is ‘talk therapy’ practices, such as cognitive behavioral therapy, which attempt to change thought patterns. It may be that having an inner voice makes it easier for some people to achieve that than for others.

“The experiments in which we discovered differences between the groups were about sound and being able to hear the words themselves,” says Nedergård.

“I would like to explore whether this is because they simply don’t experience the healthy aspect of language, or whether they don’t think in a linguistic format at all like most other people.”

The research was published in Psychological Science.

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