It is quite rare for philosophers to begin researching a new area, since many of the questions they explore have existed since ancient times. However, there is something that has not been studied closely until about 15 years ago and is located at the intersection between psychology and philosophy: inner speech.

Also known as internal monologue, it is the voice we hear in our mind when we think or read. Surprisingly, empirical research has found that although most of us have that inner voice, not everyone does .

Science and psychology have paid a lot of attention to it. For more than a century we have known that inner speech – especially when reading a text – is accompanied by small movements of the larynx , which demonstrates a clear relationship between “internal” and “external” speech.

Philosophers had already reflected specifically on the subject. The well-known behaviorist Gilbert Ryle believed that the inner voice played a key role in what philosophers call “self-knowledge.” We learn about others by listening to what they say. In his seminal 1949 book, The Concept of Mind , Ryle suggested that we are able to do the same with ourselves by “eavesdropping” on our own inner speech.

The phenomenon has appeared in other philosophical contexts, but until recently it had not been the subject of sustained attention in this field. Philosophers are realizing that there are certain aspects of the inner voice that can only be addressed through clearly theoretical thinking.

Psychology vs Philosophy

Over the years, as we have said, psychologists have paid much more attention to the topic than philosophers. The Soviet psychologist Lev Vygotsky was a very influential figure in the field. Vygotsky observed – as we have all undoubtedly seen – that children of a certain age often talk out loud to themselves, but gradually stop doing so as they grow older. He suggested that inner speech develops as this practice disappears. According to Vygotsky, the inner voice is nothing more than the internalized outer voice.

Many philosophers agree, but some see the phenomenon differently, since there is, as far as we know, no other activity that we can perform both internally and externally. Some philosophers have thought that inner speech might not actually be speech, but rather a mental representation of it.

Ray Jackendoff , for example, has suggested that we imagine what our voice sounds like when we produce the inner voice, but we do so by imitating how we would express ourselves if we spoke out loud. We are not talking, but simulating speech.

This is purely theoretical reasoning, but it is not intended to question or refute psychological approaches. On the contrary, it enriches empirical research by adding a new and valuable perspective.

Do we talk to ourselves?

One question we can answer, at least in part, is why we produce inner speech, even though no one else can hear it. There are several advantages.

Putting our thoughts into words can help us clarify them and make them more precise. Sometimes we can only work out our true thoughts by saying them out loud. We often talk to other people – or write down our ideas – to try to solve a problem or deal with emotions. Producing inner speech helps us develop our thoughts in a similar way.

It may also have other advantages. Bringing awareness to an existing thought or belief by expressing it internally can help advance a reasoning process, even about everyday matters. “If I get home at 6:30, I can make dinner at 7:30,” you may say to yourself. But this raises the following thought: “Oh, but the game starts at 7. I’d better order takeout.”

These answers, however, still leave an open question: Are we really talking to ourselves the same way we talk to others? Or do we just “talk”?

Control the voice in your head

Another field in which philosophical reflection is possible is the question of whether producing the inner voice is an action or something that simply happens.

When we physically speak out loud, it is an action: we can choose to do it or not. The same cannot be said for inner speech, which is often unprovoked, or even intrusive and unwanted.

In fact, it can be difficult to silence our internal monologue, and doing so at will is almost impossible. Check it out for yourself, right now: focus on trying not to think about anything and stop producing internal speech. You may, paradoxically, find yourself producing more, and greater efforts to stop it will only make it more difficult. Conditions such as stress , anxiety or depression have also been shown to have psychological links to inner speech.

We can decide to produce a particular fragment of the inner voice – “say” a word in our mind – but it often seems to happen without us doing anything at all.

What is an action?

In my research I have argued that producing inner speech is almost never an action, although the question of what makes something an action is itself a topic of philosophical debate.

One prominent theory holds that actions are things we can try to do or that require effort. Producing inner speech is often effortless and, as we have seen, it is difficult for us to even stop it. This seems to indicate that it is not something we try to do, but rather it just “happens.”

Other theories of action yield a similar result: inner speech almost never fits the definition.

An enormous amount of philosophical work has been done on the topic of conscious experience in general. However, philosophers have not always paid attention to specific mental phenomena. The inner voice is a unique type of conscious experience, which appears to involve a typically external activity – speaking – that takes place in the mind. Investigating it will undoubtedly take us down fascinating paths in years to come.

Author Bio: Daniel Gregory is the María Zambrano Postdoctoral Fellow at the University of Barcelona