In the comedy The Switch, the protagonist early on briefly encounters a homeless person who appears to be narrating his inner thoughts out loud, in a continuous, verbal, stream-of-consciousness. Taxi. Taxi driver. Taxi, taxi, taxi, taxi. Fat, pedaling, hooker-looking bitch. Pig-faced… Pig-faced, gimpy, limping mama. Man-boy. Little man-boy. Beady-eyed little man-boy. Beady-eyed little man-boy looking at me…

This isn’t just the stuff of comedy. A similarly afflicted gent occasionally wanders the aisles of a local supermarket, muttering his inner monologue out loud. It’s simultaneously hilarious and tragic.

After all, imagine if you were forced to voice your inner thoughts out loud, constantly.

Still, be glad you have inner thoughts to potentially voice. Astonishing as it may seem, not everyone does.

Previously, it was commonly assumed that having an inner voice had to be a human universal. But in recent years, researchers have become aware that not all people share this experience.

Estimates of the prevalence of this condition vary: some claim as many as 50 to 70 per cent of people don’t have an inner voice. This seems, on the face of it, implausible: if only for the simple fact that people would have noticed a long time ago. Research estimating a much lower percentage – five to 10 per cent – seems more likely.

So, how does it affect them?

According to postdoc and linguist Johanne Nedergard from the University of Copenhagen, people describe the condition of living without an inner voice as time-consuming and difficult because they must spend time and effort translating their thoughts into words:

“Some say that they think in pictures and then translate the pictures into words when they need to say something. Others describe their brain as a well-functioning computer that just does not process thoughts verbally, and that the connection to loudspeaker and microphone is different from other people’s. And those who say that there is something verbal going on inside their heads will typically describe it as words without sound.”

In the field of Philosophy of Mind, this is particularly fascinating. After all, how do non-verbal creatures like dogs, cats or apes think? Is an inner “Cartesian theatre”, complete with narration, what distinguishes human consciousness? Presumably not, as the non-inner voice people seem to suggest.

But, the new research shows, lack of an inner voice – technically anendophasia – does bring its own difficulties. Mostly, in performing verbal memory tasks.

People who reported that they either experienced a high degree of inner voice or very little inner voice in everyday life were subjected to one experiment that aimed to determine whether there was a difference in their ability to remember language input and one about their ability to find rhyme words. The first experiment involved the participants remembering words in order – words that were similar, either phonetically or in spelling, e.g. “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,” Johanne Nedergard explains and continues:

“And this hypothesis turned out to be true: The participants without an inner voice were significantly worse at remembering the words. The same applied to an assignment in which the participants had to determine whether a pair of pictures contained words that rhyme, e.g. 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.”

The condition would also presumably make mnemonic learning, the sort of nursery-rhyme stuff we become accustomed to at a young age, much harder. For instance, try recalling how many days are in November without reciting the poem in your head.

Certainly, though, such people aren’t stupid. In some tests, anendophasic people performed little differently to the rest. It turned out that they typically find workarounds.

“Maybe people who don’t have an inner voice have just learned to use other strategies. 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,” Johanne Nedergard says.

Science Daily

According to Nedergard, the differences between people with and without an inner voice will not be noticed in ordinary conversation.

It’s suspected that the difference may be important in the field of cognitive behavioural therapy, a widely used form of psychological therapy. CBT relies on subjects identifying and changing adverse thought patterns. Having an inner voice may be very important in such a process.

At present, though, this is just speculation. Anendophasia remains, then, a fascinating if poorly understood condition.

Punk rock philosopher. Liberalist contrarian. Grumpy old bastard. I grew up in a generational-Labor-voting family. I kept the faith long after the political left had abandoned it. In the last decade...