Research sheds light on the voices in our head

Talking to ourselves in our heads may be the same as speaking our thoughts out loud.

Research sheds light on the voices in our head
We spend a lot of our time talking to ourselves in our heads. Photo: UNSW Science

Most of us are familiar with the experience of silently talking to ourselves in our head. Scientists called this phenomenon as inner speech. As far as our brain is concerned, talking to ourselves in our heads may be fundamentally the same as speaking our thoughts out loud.

According to a new research by UNSW, talking to ourselves in our heads may be fundamentally the same as speaking our thoughts out loud. It could also help understand why people with mental illness like schizophrenia hear voices.

Study first author Associate Professor Thomas Whitford said, “It has long been thought that these auditory-verbal hallucinations arise from abnormalities in inner speech – our silent internal dialogue.”

“This study provides the tools for investigating this once untestable assumption.”

When we get ready to stand up boisterous, our cerebrum makes a duplicate of the guidelines that are sent to our lips, mouth and vocal ropes. This duplicate is known as an efference-duplicate.

The copy then sent to the brain that processes sound to predict what sound it is about to hear. This allows the brain to discriminate between the predictable sounds that we have produced ourselves and the less predictable sounds that are produced by other people.

Associate Professor Whitford said, “The efference-copy dampens the brain’s response to self-generated vocalizations, giving less mental resources to these sounds because they are so predictable.”

“This is why we can’t tickle ourselves. When I rub the sole of my foot, my brain predicts the sensation I will feel and doesn’t respond strongly to it. But if someone else rubs my sole unexpectedly, the exact same sensation will be unpredicted. The brain’s response will be much larger and creates a ticklish feeling.”

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