What is inner speech?
What is inner speech?
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Introduction
Introduction
The National Institutes of Health defines inner speech as "the subjective experience of language in the absence of overt and audible articulation."
In other words, it's words you think silently to yourself.*
"The Thinker," a statue built in 1880 by Auguste Rodin. It's possible the stone man is experiencing inner speech as a part of his deep thoughts.
Dilemma!
Dilemma!
So... what really is inner speech? There are a few issues with that question.
*Some people might argue that speaking out loud sounds the same as inner speech, but others think it is completely different. Some people think it is thought itself, and some people think it is a window into how we think. The research we will look at suggests that inner speech has a lot of functions, and depending on the person, it can vary wildly.
And inner speech is really hard to research because we cannot accurately measure what is happening in someone’s inner monologue/dialogue without that person telling us. It is hard to test if someone is following the instructions when you tell them to think a certain way, or to tell what exactly they are thinking. On this page, we are going to look at some ways researchers have tried to measure and examine it. Keep in mind that we are still trying to figure out the best way to measure it.
Starting from the beginning: Plato to Vygotsky
Starting from the beginning: Plato to Vygotsky
How long has inner speech been studied? And when was it first observed?
As far as we know, this phenomenon goes back to the beginning of human language. But we only have records of inner speech from when humans started keeping records. As early as the ancient philosophers Plato and Socrates, references to "internal language" (think inner speech) v.s. "external language" (think external -- conversations with others) (for the curious, λόγοςἐνδιάθετος and λόγος προφορικός respectively in the original Greek) were being made -- this is as early as 400 BCE -- for context, 400 BCE is around when historians think the first catapult was built.
But psychological research on these concepts begins much much later; the most important historical figure to know here is Lev Vygotsky (1896-1934), a psychologist from the USSR (present-day Russia). He also observed this phenomenon of self-talk, or internal dialogue. He thought that inner speech is inspired by our social interactions with others, so children start life surrounded by others, learn to talk to them, and then eventually start talking to themselves in the way they do others. We'll talk more about this developmental process in the next section.
Vygotsky's theory was a direct contradiction to psychologists like the American John Watson (1878-1958), who said that it is just very quiet talking to oneself (so quiet that it becomes silent). Unlike Watson, Vygotsky thought that inner speech and external dialogue are different, and that inner speech is not just a simple conversation with oneself, but a way to self-regulate, or to act like a responsible parent/teacher for oneself.
Vygotsky argued that the following three things happen when we think internally (as opposed to speak out loud):
The three concepts: we make things shorter when we think, and words have special meaning to us (in the "interview" example, interview means the feeling of anxiety to the thinker), and that meaning (often) takes priority over the dictionary definition of the word.
Importantly, Vygotsky creates three categories for speech: external speech (speaking out loud to other people or things), private speech (speaking out loud to oneself), and inner speech.
Vygotsky has some interesting ideas about how inner speech develops, too -- but we'll save that for the next section (it's linked here if you want to skip to it now: Inner Speech Development)
Statues of ancient Greek philosophers, some of whom wrote about inner speech.
Lev Vygotsky, Soviet psychologist who created the base for our current understanding of inner speech.
A really great video by a great inner speech researcher, Dr. Charles Fernyhough. Click on it for his perspective on the topic.
Post-Vygotskian inner speech research
Post-Vygotskian inner speech research
What is our modern understanding of inner speech?
Since Vygotsky, technology has advanced further. Interestingly, though, the current consensus is that his theories on inner speech development (in the next section) and his ideas about how inner speech is different from external speech are still widely supported.
Psychological research has mainly expanded on his ideas; for example, as you'll see in the next section, the living psychological researcher Fernyhough took Vygotsky's idea of inner speech and split it into two subsections, "condensed" and "expanded" inner speech.
His research with his colleague took Vygotsky's concepts and married it with some modern ones! See below :
The modern understanding of inner speech: a figure from Alderson-Day and Fernyhough's paper in 2015. This integrates Vygotsky's model (external speech/private speech [see next section for more detail]/inner speech) with some other concepts from memory research and more recent developments in our understanding of inner speech. "maintained via rehearsal" just means that we remember things by thinking about them repeatedly ("rehearsal").
And with our fancy new brain imaging technology and machines to do our statistics, we've been able to localize inner speech to specific sections of the brain, observe inner speech across languages and cultures, and examine patients with a variety of conditions to see how their inner speech works. For how we've done that, take a look below!
How do we learn about how inner speech works?
How do we learn about how inner speech works?
How scientists study how we think - and some self-testing opportunities
So how do we really know all of this? What were the researchers doing in their experiments to learn about inner speech? The following are some methods that they used to pick the brains (or more specifically, pick the thoughts) of their victims experimental subjects.
Questionnaires/surveys
The first, most straightforward, and cheapest way that scientists take a look at our thoughts is by asking us what we are thinking. After a lot of trial and error, they have developed a few different sets of questions to ask people about their thoughts, and put them into categories.
An example of a modern survey to examine inner speech is the VISQ (Varieties of Inner Speech Questionnaire), which was developed by Fernyhough, the guy from before, and a psychiatrist named Dr. Simon McCarthy-Jones. It allows scientists to get a number for how much someone's inner speech includes dialogue (two or more "voices" talking to each other), whether or not the speech is encouraging or discouraging to the thinker, and whether or not other real peoples' voices are a part of the inner speech. Check out the link on the right to take the VISQ yourself!
While this way of looking at inner speech is a great way to get a lot of data really quickly, it can have some issues; for example, there is no way to know if someone is misunderstanding the question or lying on the survey about their own experience 🤔
"Phonological judgements" -- your inner hearing
Researchers can also use this method to study how our inner speech works. They have people make judgements about sentences based on just silent reading. For example, in a phonological judgements experiment, a researcher might have people read a poem silently and then pick which words rhyme (test yourself! check out the picture from the children's book on the right)
Researchers used this method to figure out if people with aphasia (who have lost their ability to speak) can still "hear" their inner speech, and to tell if people with accents have those accents when they think silently to themselves. If you want to know what they found, keep reading! The answers are in the FAQ.
"Experience Sampling" - fancy diary method
This type of gathering data, like surveys, involves a participant recording their own experience for the researchers (self-report). It's different, though, because participants usually record information multiple times at random times.
For example, researchers might have a participant wear a beeper around that randomly goes off at times during the day. When it goes off, the participant writes down whatever it is they were thinking to themselves. This is a great way to get more data from one person over time, and might eliminate some issues with the survey data (for example, a person's mood may change throughout the day and so their thought content will change -- a survey that only gets data at one point in the day wouldn't account for that).
Some researchers who wanted to learn more about how athletes think used this method with golf players. They ended up finding that golf players recorded more inner speech during tournaments when compared to their regular practice.
Examining how people speak to themselves (out loud) - private speech as a sign of inner speech
As we will examine in the next section, many researchers (including Vygotsky) argue that private speech, or the act of speaking out loud to oneself, is a version of inner speech that we can hear. So some research has taken that concept and ran with it by looking at how people talk to themselves as a way to examine their inner speech.
For example, a researcher used this method to see how inner speech development might change in groups of children with and without difficulties with math. They looked at how these children talked to themselves (and then eventually switched to silently thinking to themselves) and found that children with math difficulties did not show a transition from private speech to inner speech, and that children without math difficulties did. It's important to note that the researchers weren't sure if math difficulties caused less inner speech development, if the lesser inner speech development caused the math difficulties, or if there's some third cause that affects both math difficulties and inner speech.
For some of the results from their study, see the graph on the right ->
A benefit of this kind of study is that if researchers are primarily looking at private speech, this is something they can record. There is no concern about subjects falsely reporting, since the recording is all done by the researcher in charge.
Multitasking - "dual task methods"
This method is exactly what it sounds like -- researchers have participants do two things at once. One thing is the task that they want to measure results for and the other is something that is supposed to stop people from using their inner speech.
For example, some researchers wanted to see how much children rely on inner speech for problem-solving. To test this, they had children solve the Tower of London task on the right -->
while either saying their own name or a random word over and over again (this is the task that is supposed to stop them from using inner speech) or not saying anything.
To play the Tower of London game yourself, click on the image on the right! Maybe even try saying your own name or a random word over and over again while playing to see how it affects your results.
Click the link above to take the VISQ yourself! Unfortunately, this website won't give you an interpretation of your results, but it is a cool way to see what type of questions that researchers ask us about our thoughts.
A children's book. The sentences at the bottom of each page rhyme if the reader speaks (uses inner speech in) Australian English.
A golfer verbally thinking to himself (inner speech). Experience sampling research suggests he might do this more when he's in a competition.
A graph from a private speech study. The left side is a group children with math difficulties, and the right side is children without math difficulties. The children without math difficulties showed more private speech and then more internal speech as they got older, where the children with difficulties did not (the white bar gets bigger on the right side, but doesn't on the left).
The Tower of London task used in the dual task methods study. Click the image to try playing yourself!
Inner speech in the brain!
Inner speech in the brain!
Another very cool way that scientists have looked at how we think is by taking pictures of people's brains while they think (neuroimaging).
A word of caution: fMRI, the type of picture that we are about to look at, takes a while to get a picture. So for time-sensitive things to measure, like a moment of shock, its results should be taken with a grain of salt. A lot of our information for where inner speech happens is from fMRI studies.
The brain:
Human brain.
On the left is a brain.
When we use our inner speech, a few different areas get activated.
First, the auditory cortex (in yellow) shows more activation. The auditory cortex activates when we process sound (i.e. when we hear things). It is interesting that it gets activated because we are not actually "hearing" anything from outside. Researchers found that inner speech uses the same brain areas as when we hear others' speech!
Second, inner speech has also been found to activate Broca's area (in pink). Broca's area activates when we produce speech! Like the auditory cortex above, it's interesting because even though we are not actually speaking aloud, it activates. So inner speech uses similar areas brain-wise to our own out-loud speaking too!
Third, inner speech activates the motor association area (in light pink). The motor cortex mainly plans our physical action for us. Researchers argue that is because it is a type of speech - a special type of speech, and speech is an action.
Whether or not inner speech and speaking out loud use these parts of the brain the same way is still up for debate.
References (click on the links to see the original sources!)
Alderson-Day, B., Weis, S., McCarthy-Jones, S., Moseley, P., Smailes, D., & Fernyhough, C. (2016). The brain's conversation with itself: neural substrates of dialogic inner speech. Social cognitive and affective neuroscience, 11(1), 110–120. https://doi.org/10.1093/scan/nsv094
Dickens, Yani & Vanraalte, Judy & Hurlburt, Russell. (2017). On Investigating Self-Talk: A Descriptive Experience Sampling Study of Inner Experience During Golf Performance. The Sport Psychologist. https://doi.org/10.1123/tsp.2016-0073
Ehrich, J. F. (2006). Vygotskian Inner Speech and the Reading Process. Australian Journal of Educational & Developmental Psychology, 6, 12-25. https://eric.ed.gov/?id=EJ815614
Filik, R., & Barber, E. (2011). Inner speech during silent reading reflects the reader's regional accent. PloS one, 6(10), e25782. https://doi.org/10.1371/journal.pone.0025782
Gacea, Alexandru Ovidiu . Plato and the ”Internal Dialogue”: An Ancient Answer for a New Model of the Self. L. Pitteloud, E. Keeling (dir.). Psychology and Ontology in Plato, 139, Springer International Publishing, 2019, Philosophical Studies Series, 978-3-030-04653-8. ff10.1007/978-3-030-04654-5_4ff. ffhal-01975795
Lidstone, J. S., Meins, E., & Fernyhough, C. (2010). The roles of private speech and inner speech in planning during middle childhood: evidence from a dual task paradigm. Journal of experimental child psychology, 107(4), 438–451. https://doi.org/10.1016/j.jecp.2010.06.002
McCarthy-Jones, S., & Fernyhough, C. (2011). The varieties of inner speech: links between quality of inner speech and psychopathological variables in a sample of young adults. Consciousness and cognition, 20(4), 1586–1593. https://doi.org/10.1016/j.concog.2011.08.005
McGuire, P. K., David, A. S., Murray, R. M., Frackowiak, R. S. J., Frith, C. D., Wright, I., & Silbersweig, D. A. (1995). Abnormal monitoring of inner speech: a physiological basis for auditory hallucinations. The Lancet, 346(8975), 596–600. https://doi.org/10.1016/S0140-6736(95)91435-8
Ostad S. A. (2015). Private speech use in arithmetical calculation: relationship with phonological memory skills in children with and without mathematical difficulties. Annals of dyslexia, 65(2), 103–119. https://doi.org/10.1007/s11881-015-0103-1
Stephane, M., Dzemidzic, M., & Yoon, G. (2021). Keeping the inner voice inside the head, a pilot fMRI study. Brain and behavior, 11(4), e02042. https://doi.org/10.1002/brb3.2042
Whitford, T. J., Jack, B. N., Pearson, D., Griffiths, O., Luque, D., Harris, A. W., Spencer, K. M., & Le Pelley, M. E. (2017). Neurophysiological evidence of efference copies to inner speech. eLife, 6, e28197. https://doi.org/10.7554/eLife.28197
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