What Causes The Voice in Your Head?

Hey Thoughty2 Here. Do you ever talk to yourself? No, not out loud, in your mind. I’m talking about that little voice in your head that often chips in throughout the day to offer up some useful advice. You know, the one that’s saying “I hate you” over and over again whilst your boss is giving you a mighty fine rollicking. Sometimes we even have entire conversations with ourselves in our heads. We can also hear it when we read, it’s as if our mind is saying the words out loud but only you can hear it. What causes that little voice inside your head and what’s its purpose? Let’s find out. You might call it Barbara or Keith but scientists actually have a proper name for the voice in your head. It’s called “inner speech” and it’s been a topic of extensive research for centuries. Psychologists in particular have been obsessed with it ever since psychology began. In the 1930s Russian psychologist Lev Vygotsky put forward the case that inner speech is a result of the internalisation of external speech. Or to put it in other words, he thought that inner speech is the exact same process as external speech, right up until the point where noise exits our mouth. There may be some truth to this theory. In the nineties neuroscientists used neuroimaging techniques to discover that an area of the brain called “Broca’s area” which is responsible for fine motor skills involved with speech, was active during inner speech as well as normal speech. This means that the muscles and organs that move when we speak, such as the larynx, also move when we speak to ourselves in our minds, despite there being absolutely no reason for such muscles and organs to do so. This can only mean that the systems in our brain that govern external speech and inner speech are very closely linked or maybe even the same. The two systems are so intrinsically linked for good reason. Because inner speech is actually a prediction of what we’re about to say. Researcher Mark Scott at the Department of Linguistics at the University of British Columbia led a stud which explored a brain signal known as “corollary discharge”. This signal is a copy of a motor signal that is sent to the brain to alert the brain that we are about to move, so the brain knows to react accordingly and most importantly not to overreact. The purpose of corollary discharge is to separate sensory experiences that come from outside our body and ones that we produce ourselves. It allows our brain to predict our own movements before we actually make them. This is why we can’t tickle ourselves. Because, before you even start to tickle yourself a corollary discharge signal has already been sent to your brain to alert it that you’re about to tickle yourself and so your brain completely ignores the sensation of being tickled. The system is primarily used to determine the difference between an external threat and something that we do ourselves and should therefore be considered non-threatening. Our brain utilises corollary discharge in a very ingenious way when we speak. If corollary discharge didn’t exist, when we talk our voice would be overwhelmingly loud. Because our ears are so close to the source of the sound, our own voice would appear so loud that it would drown out every other noise around us, and we wouldn’t be able to hear anything but our own voice and no matter how much some people love the sound of their own voice, that would get bloody annoying. However, when we speak corollary discharge is used to predict that we are going to produce a noise and so our brain dampens the sound of that noise. The result is that our own voice sounds quieter to us than to everyone else. Amazingly our brain does this self-voice filtering without affecting the volume of voices from other people. So why do we have a voice inside our heads? Ours brains are able to plan sentences in our minds before we actually say them. The brain is also really good at replaying sounds we’ve heard before. Try imagining any sound you’ve heard before throughout your life, be it a police siren or birds tweeting. When you think about these past sounds you can actually hear it, it’s almost as if it’s being replayed inside your head. So when our brain plans a sentence it replays the sentence inside our head, and this is what we refer to as the voice in our head, or inner speech. Because of corollary discharge the brain knows which sentences should be spoken out loud and which are meant for our ears only and therefore should be replayed as inner speech in our mind. The brain heavily utilises inner speech when we read because it helps our brain to better understand the words on the page and remember them. Scientists believe people with dyslexia have a harder time reading and understanding words because they have no inner voice. It may be hard to imagine but most dyslexic people don’t understand the concept of a voice inside their head, because they quite simply don’t have one, they instead visualise and understand everything in pictures instead of words. For most people inner voice is an automatic process and we can hear it every minute of the day, narrating our lives, planning and predicting what we’re about to say and communicating to us what we are reading in real-time. Some dyslexic individuals have no grasp of this concept and simply don’t experience it, that’s why they often move their mouths whilst reading, because they don’t have the luxury of a voice inside their head reading it for them, to help them to easier understand the text. Young children do the exact same thing because we don’t develop the skill of an inner voice until later on in childhood. Until children learn this skill they tend to say everything out loud, for better or for worse. It may at times seem like a little devil inside your head, coercing you to do unruly things, perhaps telling you to “punch your boss in the face, go on do it”. But it is in fact just your brain planning and even predicting what you’re about to say, even if you don’t end up actually saying it. Because it may be the case that only you need to hear it, and let’s be honest that’s usually for the best.