Scientists can now cause people to hear phantom voices.
Generally, 5-10 percent of healthy individuals hallucinate, according to a recent series of psychiatric surveys conducted in Norway.
But to understand why, a team of scientists in Switzerland have now tested the Link between the senses of touch and hearing, using a finger-like robotic system to find out what makes people ‘hear things’ or feel a presence in the room a common form of hallucination.
Healthy Volunteers would push a button to stimulate the movement of a device in the lab: a robotic ‘finger’ behind them that would give the test subjects a small tap on the back.
Typically, there were short to no delays between each button push and the poke — but when there was a delay, participants would activate that sixth sense, feeling as if someone was close to them speaking.
Across two tests involving 48 subjects, more people were likely to report ‘vocal false alarms’ when their backs had been prodded with more unexpected pokes.
Even healthy individuals may hallucinate, whether they feel as if something is touching them or they hear the nonexistent voices of strangers, as if they are nearby
Hallucinations can come in many forms such hearing things, seeing faces, animals or even feeling that a bug is on your arm. This ‘sense’ that something may be happening is more common than you might think.
Taste, smell, vision, hearing and touch make up our five senses. But we also have a sixth sense: proprioception—your body’s awareness. And part of this sixth sense is our ability to hallucinate.
“There is actually a continuum of these experiences,” Dr. Orepic told the New York Times. “So all of us hallucinate — at certain times, like if you’re tired, you’ll hallucinate more, for instance — and some people are more prone to do so.”
According to the study, published in Psychological Medicine, participants were more likely to report hearing a voice when there was no voice if they had already started to have a ‘weird’ feeling of something close to them.
Besides poking individuals, the participants asked to report when they heard human voices within ‘pink noise’ played in the room—equivalent to the depth of heartbeats or wind blowing.
Some of these fragmented recordings did include either their own voice, a stranger’s voice mixed within the ambient sound.
The researchers also found that when a voice recording with background noise was played for a participant, then later in the experiment the individual was more likely to hallucinate voices during other recordings.
Some participants who pushed the button in front of them to trigger the robotic ‘finger’ claimed to have also heard voices when there was no delay and when there were no voices.
The researchers say this could have been because of an inert feeling if the participants were ‘unconsciously’ controlling the robotic system and thought to have heard their own voice.
Even in these healthy individuals who have no history of neurological disorders or hearing loss, the study suggests that hallucinations may be more common when someone struggles to understand their body’s awareness or proprioception.
With a pocket in the brain used to store memory, the researchers suggest that when participants held onto the previous parts of the trial, impacted their sixth sense later in the environment.
This investigation could ‘shed new light’ on voice and touch hallucinations, the researchers say.
Maybe the next time you are running through Central Park with the presence that someone may be behind you or that the birds singing in the treetops aren’t the only tunes you are hearing, you may be experiencing something that many other people around the world experience.
