How does hypnosis work?

When you think of mind control, there’s usually one thing that immediately comes to mind. Hypnosis. This is the spooky phenomenon where people can appear to be under someone else’s control. But is it real? Ever curious, the Naked Scientists decided to give it a go and had their first taste of being hypnotised by stage magician hypnotist Jack Blackbourne…

Jack - I want you to imagine now these magnets going to get stronger and stronger. What's going to happen is its going to start pulling your hands in closer and closer together. Deep breath in with me. These are real big stack of heavy books, imagine your hand now getting heavier and heavier. If you try and pull your fingertips apart, it's going to feel almost impossible to do so; the more you think about it and the stronger these magnets feel, if you try and pull your fingers apart it's going to be really really hard to do so. One, two, three, now open your eyes.

Georgia - Despite being a bunch of skeptics that were definitely a few fingers stuck together and a hand or two floating up in the air. All thanks to the dark arts of Jack Blackbourne, professional hypnotist and mind reader who started getting into it about seven years ago.

Jack - There is a hypnotist school, like Hogwarts but for hypnotists, you can go on a big crash course over a few days and two days later you come out of it and you're a hypnotist. Easy as that really.

Georgia - What was it like for you the first time you actually hypnotised someone?

Jack - Scary as you could imagine, the fear of failing in front of everyone, but the first time it works and you just have this overwhelming sense of wow, I've got like a superpower now.

Georgia - Were you tempted to use your powers for evil?

Jack - I still do. Not tempted, I still do. Yeah I went into a bar and got someone who I had never met to give me all his money in his wallet, for no reason at all other than to make him feel great.

Georgia - Did you give him his money back?

Jack - Of course I did yeah.

Georiga - What's your favourite thing you've ever got someone to do?

Jack - It depends on the situation. There's the situations where we get like a stag party or a hen do and everyone's up for something; everyone's up for a laugh and everyone's up for a bit of mickey taking and you can get them to do whatever you want, you can get them to pretend like they're baby again and they'll just crawl down on the floor and they'll make lots of noises and not talk like a human being. That's kind of fun in front of lots of burly men who are drunk, to see that they're kind of the best man for example, rolling down the floor crying. Yeah that that's always a good one...

But what is hypnosis? Chris Smith spoke with Devin Terhune who researches the subject at Goldsmiths, University of London...

Devin - Hypnosis means a lot of different things depending on the usage and depending on the person using it. Typically in an experimental or clinical context it refers to a set of techniques in which we harness the phenomenon of suggestions. We use suggestions to alter behaviour and experience. So suggestions are just simple verbal communications whereby we're telling you something that you're going to experience something as though it's occurring outside of your control. So I might tell you for example you are no longer able to experience anything in your arm and in very highly suggestible individuals, this can often produce an experience where they cannot feel any pain for example in their arm. Hypnosis is just a technique for using those suggestions.

Chris - And what do you mean by highly suggestible. What does that actually translates into? How would I recognise someone who is?

Devin - They are not necessarily easy to recognise on the street, so they don't have any kind of distinct kind of characteristics that are easily identifiable. Nevertheless they amount about to about 10 to 15 percent of the population. So these are people that are able to experience pronounced changes in their thoughts, their emotions, their perception in response to suggestions kind of one of the most notable features of them is they tend to get very highly absorbed in activities, so people that tend to kind of get really emotionally involved in films or music and activities along those lines, tend to more often not be more highly suggestible.

Chris - And do we understand why, when you make these suggestions to them they are more susceptible to engaging with that message. Is this something about their brain that makes them susceptible?

Devin - Sure, so our understanding of the of the brain mechanisms underlying hypnosis are relatively poor. We do know that suggestibility is fairly stable and so this would seem to suggest that are there are these kind of neuro-physiological characteristics. One kind of idea that there's behavioral evidence as well some neuroimaging evidence, is that highly suggestable individuals seem to have less awareness of their intentions. So normally when I try to suppress pain in my arm I'm aware that I'm intending to do so. So one kind of prominent theory of hypnosis that we would suppress pain in the arm, but a highly suggestible person is not aware that they're doing so, and that's why it feels like it's outside of their control. So this seems to kind of implicate brain regions or brain networks involved in the extent to which we're aware of our own mental states.

Chris - To what extent have people actually done hypnosis in brain scanners to see how it changes brain activity?

Devin - There's been a tremendous amount of research using functional neuroimaging techniques to study various features of hypnosis, has been going on since the mid to late 90s. These studies have largely aimed to kind of validate hypnotic responses and less to study the mechanisms. So basically in other words these techniques have largely shown beyond fairly reasonable doubt that when people are experiencing a reduction in pain in response to hypnosis, you're actually seeing corresponding changes in brain regions supporting pain processing. So basically these kind of studies overwhelmingly indicate that hypnosis is a real, in the sense that's producing genuine changes in the brain.

Chris - And if it's producing genuine traces and changes in the brain what's the application? And in what way can that be used for good not just to make people laugh on stage. Can we use it clinically?

Devin - Yes so the primary clinical application of hypnosis in therapeutic contexts perhaps the most prominent one is in the treatment and management of pain. So since the 19th century hypnosis been reliably used to treat and manage pain. It's important to emphasise it's certainly not a panacea, it doesn't work with everyone and it's not going to work with all conditions and symptoms. It's especially good with pain. The evidence for other conditions such as anxiety and depression is not really as good. That might be because there's not a lot of research on that. So it's really hard to say but particularly in the context of pain it seems to be especially valuable. 

Chris -And to finish do you think it's just humans that are susceptible to hypnosis. Could I for instance hypnotise my dog?

Devin - I would say you cannot know. So I would view hypnosis as largely a kind of a verbal application of suggestion. Certainly you could potentially manipulate your dog in various ways and potentially manipulate their behaviour using various types of tricks, but I would be very cautious about kind of linking that with something like hypnosis.