The voice we hear in our head comes in many forms. It can psyche us up for a big interview, help us remember an important speech, or guilt-trip us into calling our grandparents more often. The researchers behind the Hearing the Voice project believe that studying the science behind inner speech will give us a better understanding of language, mental illness, and ourselves.

Researchers at Durham University in England have been developing the project since 2010. Their scope stretches far outside the medical world with team members hailing from the fields of neuroscience, English literature, medical humanities, philosophy, psychology, and theology. One of the main goals of the project is a better understanding of inner voices as they relate to mental disorders, and one way they’ve been doing that is by studying the voices we all hear on a daily basis.

Scientists already know that inner speech shares a lot of similarities with externalized speech in terms of what’s happening with our brains and bodies. When that voice “speaks” in our head, our larynx is making subtle muscle movements to accompany it. The same part of our brain we use to speak out loud is also active when we speak internally.

Knowing this, researchers can compare what’s happening to the brain when speaking aloud to what happens to it during auditory verbal hallucinations (a term often used to describe the voices heard by people suffering from mental illness). One recent study was conducted by scientists in Finland in which they scanned the brains of participants experiencing such hallucinations then asked them to purposely imagine the same voice. The experiment showed that while similar parts of the brain did light up, the main difference was in the supplementary motor area, which was much less active when the subjects heard voices. This supports the theory that we rely on signals from this part of the brain in order to recognize an inner voice as “ours.”

Looking at neuroscience is important to the Hearing the Voice project, but listening to and discussing first-hand experiences is also a huge factor. Last year, Hearing the Voice teamed up with Edinburgh’s International Book Festival to look at the experiences of hearing inner voices from the perspectives of writers and readers. The event included interviews, workshops, and panel discussions aimed at shedding light on the subject.

After receiving another five years of funding this spring, the Hearing the Voice project is continuing to find creative ways to explore the internal voices that affect us all.

[h/t: The Guardian]