‘Hearing voices’ or ‘Auditory hallucinations’ is always seen as a sign of someone without a ‘healthy’ or ‘sound’ mind. Yet, many misunderstand what these experiences truly represent. Auditory hallucinations are basically hearing a sound that isn’t there. According to the Schizophrenia Research journal, about 60-80% of people who are on the schizophrenia spectrum experience these. However, do you know where these ‘voices’ come from? A major new study published in the journal Schizophrenia Bulletin gives the strongest proof yet that when people with schizophrenia hear voices, they are actually mistaking their own silent thoughts for sounds coming from outside. Their brains respond more strongly when their inner voice aligns with an outside sound. Individuals with schizophrenia who recently experienced auditory hallucinations had a much bigger brain reaction when their inner voice matched an outside sound. What Causes Verbal Hallucinations? The study, which was done by psychologists at UNSW Sydney, suggests that the problem of hearing voices, called auditory verbal hallucinations, happens because the brain has trouble figuring out that the silent voice inside their head belongs to them. What is Inner Speech? Inner speech is just the silent voice that goes on in your head, like a narrator for your thoughts, plans, and everything you notice. Most people have this running all the time. The Normal Brain Filter When a person speaks, even if they only speak silently in their mind, the part of the brain that deals with outside noises calms down. This happens because the brain expects the sound of your own voice and basically tunes it out so you aren't distracted by yourself. But in people who hear voices, this "filtering" process seems broken. The brain doesn't manage to predict the sound of its own inner voice, which causes it to react as if the voice is coming from someone else entirely. How Did Researchers Measure Inner Voice? For a long time, doctors have had a theory that hearing voices came from mixing up inner speech with external speech, but it was incredibly hard to test because you can't actually hear someone else's inner speech. It's totally private. Researchers used an EEG machine (which records the brain's tiny electrical signals) to secretly test this idea. They divided the people into three groups:People with schizophrenia who had very recently heard voices.People with schizophrenia who had not heard voices recently.Healthy people who did not have schizophrenia.In the experiment, everyone wore headphones and was told to imagine saying a simple sound (like 'bah' or 'bih') at the exact moment they heard one of those sounds played through the headphones. People with No Hallucinations In healthy people, when the sound they imagined in their head matched the sound that came through the headphones, the EEG showed less activity in the part of the brain that processes sound. This is the expected filtering effect—the brain recognized its own inner speech and calmed its response. Hallucination Result (The Reversal) In the group that had recently heard voices, the results were the complete opposite. When the imagined inner speech matched the external sound, their brains showed a much stronger, enhanced reaction. This backward filtering effect strongly suggests that the brain's ability to predict and filter its own thoughts is broken in people who hear voices. This failure causes the brain to see that inner voice as a loud, real sound coming from the outside. How Does Learning About Auditory Hallucinations Help Us? This discovery is very important because it offers the strongest proof yet for the idea that people's own inner speech is being mistakenly heard as an outside voice. Right now, there are no simple blood tests, X-rays, or brain scans that can definitively find or diagnose schizophrenia. These new findings give doctors hope for developing biological markers (signs in the body) that could help find or predict who is at risk of developing psychosis before it actually starts.
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