How no inner voice can affect memory

Say what?

It turns out that not everyone has an inner voice — and the 5% to 10% of the population without one may struggle to perform certain memory tests, a new study finds.

Linguist Johanne Nedergård from the University of Copenhagen and Gary Lupyan from the University of Wisconsin-Madison have coined the term anendophasia to describe the absence of conversations that most people have in their minds.

For their study, nearly 100 participants — half with very little inner voice and half with strong inner speech — were tasked with four experiments.

In the first one, participants had to remember words similar in phonetics or in spelling in order — such as “bought,” “caught,” “taut,” and “wart.” 

“It is a task that will be difficult for everyone, but our hypothesis was that it might be even more difficult if you did not have an inner voice because you have to repeat the words to yourself inside your head in order to remember them,” Nedergård explained.

“And this hypothesis turned out to be true,” she continued. “The participants without an inner voice were significantly worse at remembering the words.”

In the second test, participants had to determine whether a pair of pictures contained words that rhyme, like pictures of a sock and a clock.

“Here, too, it is crucial to be able to repeat the words in order to compare their sounds and thus determine whether they rhyme,” Nedergård advised.

However, the researchers didn’t note differences in the two groups when they were assigned to switch quickly between different tasks and distinguish between very similar figures.

This was surprising because previous research has indicated that language and inner speech play a role in those types of tests.

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

The results of the experiments were published last week in the journal Psychological Science.

Looking ahead, Nedergård wants to explore other consequences of anendophasia, like how not having a running internal dialogue could affect someone in therapy.

In “cognitive behavioral therapy, for example, you need to identify and change adverse thought patterns, and having an inner voice may be very important in such a process,” she proposed.