How brains can be tricked into hearing voices that aren’t there

We may associate hearing voices with neurological disorders, but researchers from the École Polytechnique Fédérale de Lausanne (EPFL) and the University of Savoie Mont Blanc have shown that most brains can be tricked into hearing voices that aren’t there.

A research team called Psychological Medicine aimed to investigate how auditory-verbal hallucinations (AVH) can be triggered in the mind. In the experiment, 48 participants wore headphones playing a mix of “pink noise” and occasionally snippets of voices.

The participants pushed a button in front of them, which triggered a robotic arm to poke them in the back. Some of the participants heard voices that weren’t there through the headphones.

The phenomenon was more common if the volunteers heard someone else’s voice before their own and if there was a delay between the button push and arm poke.

These results suggest that people who fail to correctly self-monitor their surroundings and are influenced by strong beliefs about what is going on around them may experience AVH.

The researchers’ findings are important in understanding how hallucinations can relate to conditions such as Parkinson’s disease and how they can be triggered.

The researchers found that the frequency of hallucinated voices that weren’t there increased with the length of the tests, implying that participants were more likely to hear the phantom sounds toward the end of the experimental session.

Although hearing voices that aren’t there may be alarming, the researchers suggest that it might not be an immediate cause for concern. However, anyone experiencing symptoms should seek medical advice to treat any underlying conditions.

Overall, the study sheds new light on AVH phenomenology, providing experimental support for both the prominent yet seemingly opposing accounts and portraying AVH as a hybrid between deficits in self-monitoring and hyper-precise priors, as written by the researchers.