The Science Behind The Voice In The Back Of Your Head

Have you ever taken a moment to think about the voice in your head that articulates every one of your thoughts and emotions? From working through complex problems to daydreaming elaborate fantasies, most of us are so used to the sound of our own internal monologue that we don’t even give it a second thought. But, as it turns out, not everyone experiences their thoughts, emotions, and internal dialogue in the same way — and those who don’t have a completely different perception of the world and themselves.

While the lack of an internal monologue does not have an official medical diagnosis, it has been proven to be linked to a condition called aphantasia. This relatively rare condition is defined as the inability for a person to create visualisations in this mind and is sometimes referred to as “blindness of the mind’s eye.” While more research is needed to determine the actual number of people living with aphantasia, some studies suggest that up to 2-5% of the population may be living with this condition, meaning that they are likely living without the ability to experience an internal monologue¹

Despite being a shared experience that many of us may not have even considered before, an internal monologue is not a universal experience for everyone around the world. As it has an impact on a person’s personality, the lack of internal dialogue is an exciting area of medical research that is still being actively explored today. 

What is an internal monologue?

Whether you refer to your internal voice as your inner dialogue, self-talk, internal speech, or stream of consciousness, an internal monologue is the voice inside your head that you can “hear” when you think. Initially defined by Russian psychologist Lev Vygotsky in the early 20th century, he believed that inner speech was a natural part of the thought process². Since then, our understanding of the internal monologue has expanded and changed as we conduct research studies to explore different facets of this fascinating phenomenon. 

For those with an internal monologue, the idea that others may not experience the same process of self-talk can often be confusing or even shocking. If you are a person who regularly experiences a robust internal dialogue, it can be hard to even remember a time when this wasn’t the case — as research shows that our inner dialogue develops and grows with us as we age. Research has shown that children as young as 5-7 are able to utilise an inner voice to process their thoughts and emotions, with other studies indicating that children as young as 18-21 months may also be able to use internal dialogue to better understand language and phonetics³,⁴.

We all experience the world in different and unique ways, and therefore it makes sense that each of us use our internal monologue for different purposes as well. While one of the most commonly reported uses of self-talk is to organise and filter through our thoughts and feelings, this is not the case for everyone. Looking to get a better understanding of how people think, a smaller 2011 study found that the specific reasons why a person uses their inner voice, as well as the frequency of their internal monologue usage, had significant individual differences, with some people reporting that they never experienced self-talk and others utilising this skill in up to 75% of the tested scenarios⁵. With this large range of results, it is hard to determine an “average” use for internal speech, as it seems that how much a person relies on their inner monologue is very personal and individualised.

The three dimensions of internal dialogue

While someone may use internal speech for a variety of different reasons, it appears that it is more closely connected with personality traits rather than intelligence. This being said, intelligence and education also play a role in how well-developed and articulate a person’s self-talk may be⁶. Looking to get a better understanding of how people use or understand their inner dialogue, a 2019 study analysed three primary dimensions of the internal monologue⁷:

• Dialogality — This dimension addresses the ongoing debate over whether it’s accurate to call this process internal speech or an internal monologue. This dimension measures how much the participant thinks in a monologue (e.g. I need to figure out this problem) versus engaging in a more multi-focal conversation or dialogue (e.g. thinking about both sides of a discussion to solve an issue). 

• Condensation — This measurement aims to understand how articulate and robust a person’s internal dialogue is. While some people tend towards using shortened words and fragments in their minds, others like to think and organise their thoughts almost like a pre-rehearsed speech or presentation. Both of these practices have pros and cons when used in different settings, which is why it is common for people to use these strategies to tackle different types of problems.

• Intentionality — This dimension measures the intention and focus of a person’s inner dialogue. At times, many people use their internal speech in an intentional way (e.g. to work through a problem or to organise their thoughts), but other times it may be more common for their self-talk to come in and out, drifting from topic to topic. 

We can “hear” our internal monologue without speaking

100% of internal speech is only experienced by the individual, and therefore researchers are  interested in learning more about how we are able to “hear” inside of our heads without having to speak. Conducting various studies at the University of British Columbia (UBC), Mark Scott found evidence of a unique brain signal called the corollary discharge — a signal that is used to determine if a sensory input was created by ourselves internally or was produced by external stimuli⁸,⁹.

Corollary discharge is a predictive signal generated by the brain that helps us better understand our environment and surroundings. This unique signal is also used as part of our auditory system, assisting in processing information and speech. As a complex system composed of many small moving pieces, the auditory system uses the corollary discharge to create an internal copy of the sound of our voice that parallels the actual sounds we make when we are speaking. 

Using this information as support for his argument, researcher Michael Scott suggests that the internal copy of our voice created by the corollary discharge could be made without the need for speaking out loud, meaning that we could hear our voice without actually having to verbalise our thoughts.

Another researcher interested in the topic of internal speech, psychologist Dr Helene Brenner hypothesises that inner speech is the result of a default mode network (DMN) in the brain. DMN is described as a network of different areas of the brain that are connected and become very active and energised when we are not completing task-oriented actions (like daydreaming or letting our mind wander)¹⁰. As it turns out, the DMN never truly shuts off, it just gets suppressed or limited when we get busy and start working through our daily list of tasks. Because of this, it is believed that the DMN is what creates our daily narrative, combining what we think about, our past and present feelings, our opinions, and more. 

Different brains experience internal speech differently (and some not at all)

Most people have some level of internal monologue going through their heads throughout their day, however there is a small group of people who do not experience any self-talk at all. While most people experience their thoughts as a sort of stream of consciousness of words and dialogue in their minds, those who do not have been reported to experience their thoughts as visualisations, broader concepts, and emotions⁵.

Current research is still unsure as to what causes some people to experience no internal monologue. Some studies suggest that in order to produce an internal dialogue, a person must have a fully functioning network of brain activity that stretches from the frontal cortex all the way down to the auditory cortex located near our ears. While this pathway is quite complex, it also is quite similar to the pathway that allows us to speak out loud, which involves our motor cortex. One theory suggests that differences in the wiring in the brain could cause a person to be unable to produce an internal monologue without verbalising their thoughts out loud¹¹

Another possible theory why some people are unable to experience internal dialogue is the concept of poor introspection. Referring to the ability for a person to examine their own mental processes and thoughts, this theory posits that everyone is capable of producing internal speech, but some are much more conscious and aware of the process than ¹¹

Is your internal monologue useful?

Because so many of us are used to experiencing our version of an internal monologue every day, it is often hard to explain precisely how helpful or beneficial this practice is to maintain our daily routines. According to psychologist Lev Vygotsky, inner speech may begin during our early years, as it is common to observe young children participating in a practice called private speech — talking quietly to themselves out loud when they are trying to work through a more complex task. He suggests that private speech is part of a four-step developmental process, with the next step moving towards expanded inner speech and dialogue⁷.

Some other common examples of the benefits and importance of the internal monologue in our growth, development, and day-to-day life include:

• As a child grows from a child to an adult, they can utilise complex internal speech to work through problems with increased efficiency. It is currently believed that a person’s internal monologue is closely linked to their language development as well as their advanced mental abilities, which would make this dialogue incredibly important to a person’s overall development.

• An inner monologue may also play a role in our working memory¹² Defined as the ability to recall transient information like phone numbers and grocery lists, having the ability to use self-talk can help to reduce the risk of forgetting information. Commonly used as a helpful memorisation or learning technique, many people have great success remembering information by reading the content either out loud or internally using their inner voice.

• This same internal voice is also essential for the practice of silent reading. When a child or adult reads a book in their mind (not out loud), they are using their internal voice to “listen” to the words that they are processing. While it is common for most people to learn how to read by practising saying the words out loud, this is a necessary skill used by billions of people worldwide every day.

• Another commonly associated benefit of an internal monologue is its use as a self-motivator. While you may or may not have heard of positive self-talk, this practice relies heavily on a person using their internal voice to provide support and praise to themselves during difficult situations. People living with conditions like anxiety and depression can benefit from this practice, as it is very easy for them to ruminate on negative feedback or thoughts that can lead to emotional turmoil. Using your internal monologue as a self-motivator and point of compassion is one of the many beneficial uses of self-talk.

On the flip side, there is research to indicate that when not properly understood or controlled, an internal monologue can lead to significant distraction and possibly even mental instability. One interesting theory regarding auditory hallucinations (hearing voices or sounds in your mind that are not truly there) suggests that people with this condition may be misinterpreting their own self-dialogue as the voices of others¹³.

Additionally, it is believed that our internal speech may play a role in having our minds wander or drift away from the task at hand. The separation of our immediate surroundings (also known as decoupling), can lead to people becoming more fixated on their internal thoughts and feelings¹¹

The key takeaways

While it was previously thought that everyone experienced a continual stream of internal thoughts and dialogue, it appears that this is not the case. Whether you struggle to visualise items without having them right in front of you, or can’t seem to escape the wandering thoughts of your mind, having an awareness of your internal monologue (or lack thereof) can be a helpful tool in improving your overall mental health and communication skills. ore research should be carried out to better understand the importance and underlying causes of our inner speech. We are looking forward to having a better understanding of how and why our internal thoughts are communicating within our minds.

Sources:

1. Conflicting intuitions may be based on differing abilities: Evidence from mental imaging research from APA PsychNet [2009]

2. Inner speech from ThoughtCo [2020]

3. Inner Speech: Development, Cognitive Functions, Phenomenology, and Neurobiology from The National Library of Medicine [2015]

4. In the Infant’s Mind’s Ear: Evidence for Implicit Naming in 18-Month-Olds from SAGE Journals [2010]

5. Toward a Phenomenology of Inner Speaking from Russel T. Hurlburt [2013]

6. Do You Have an Inner Voice? Not Everyone Does from HowStuffWorks [2021]

7. The ConDialInt Model: Condensation, Dialogality, and Intentionality Dimensions of Inner Speech Within a Hierarchical Predictive Control Framework from Frontiers in Psychology [2019]

8. Corollary discharge provides the sensory content of inner speech from the National Library of Medicine [2013]

9. Inner speech captures the perception of external speech from the National Library of Medicine [2013]

10. Apparently, Some People Do Not Have an Inner Voice—Here’s How That Happens from Well+Good [2020]

11. Inner Speech: Development, Cognitive Functions, Phenomenology, and Neurobiology from Psychological Bulletin [2015]

12. A cognitive architecture for inner speech from Cognitive Systems Research [2020]

13. Talking matters – evaluative and motivational inner speech use predicts performance in conflict tasks from Scientific Reports [2019]

The author, Claire Bonneau, is a medical writer and certified trauma operating room nurse.