Keith Barry's art of illusion

Though he is raking in a reported 300,000 viewers weekly with his 'Brain Hacker' TV3 series, the Waterford-born 37-year-old is adamant that there's little difference between him and the average man on the street.

Nothing, that is, apart from decades of cold, hard swotting up. "There has to be a level of intuition involved in what I do, and the more you use that intuition, the more honed it is," he explains over coffee in a Dublin tea shop. "The only thing is that I work harder than most people at it. But sure anyone can do what I do with 30 years of practice."

Since the age of 14, when his interest was sparked as he cracked open a book called 'Magic for the Complete Klutz', Keith has devoured books on mentalism, psychology and the subconscious.

"Even though I was studying chemistry in college, my girlfriend at the time [now his wife, Mairead] was studying psychology, and I read more of the books than she did," he says.

"I'm pretty much self-taught – I never went to any courses. If I want to learn about, say, the frontal lobe, I'll buy 40 books and absorb them in a couple of weeks. I'm a nerd like that."

Chemistry appears an unorthodox subject for an aspiring mentalist, I venture. "My parents were like, 'Magic is great as a hobby, but you're going to college whether you like it or not'," Keith replies. "What can I say? I was good at school, so that's what I did."

TV3's 'Brain Hacker' is not his first foray into mind-reading – he has been doing this for years. A decade ago, I interviewed him in the Westbury Hotel where, like most of the people who encounter him, I asked for a demonstration of his skills close up.

Asking me to write a word, any word, on a piece of paper, I scribbled down 'heart', folded it and handed it to him. A minute later, after seemingly looking into my eyes, he 'recalled' the word. Cue much spooked screeching. In the years since I had always assumed that, via body language or suggestion, he had somehow implanted the word into my brain.

"Ah, or maybe you were doing something and I was just reading you?" Keith offers. Though he won't be drawn on the whys and wherefores, he does acknowledge that, if you look hard enough, the knowledge is there for the taking.

"Sometimes I implant thoughts, sometimes I extract thoughts, but I don't like to explain it too much," he says. "It's based on science, deduction and reasoning – it's a bit like what 'Sherlock' does, except that's a dramatised version. I look at every clue around me."

He points to the teapot on the table. "Like, what way the teapot is on the table tells me if you're left or right-handed. I look at your hair colour, purse, bag – the jumper that tells me you might be cold. By using these things, I can get you to focus on a specific thought, and then I can extract that thought. Plus, we're all more alike than we like to think."

Given that it's more straightforward than first meets the eye, could a layperson use this power in everyday life for the greater good? Would it be possible, say, to get a promotion from your boss simply through implanting a thought and extracting a 'yes'?

"Oh yes, conversational hypnosis and neuro-linguistic programming are real techniques," Keith says. "You need to talk like your boss and copy their actions, like if they cross their legs, you do the same. If people think you're like them, you're more inclined to get what you want out of them.

"I also use the hypnotic anchoring system." Ya what now? He changes tack: "It's a dull day out, right?" Right. "You were having problems with your Dictaphone earlier. You should probably get a new one, right?" Yes. "Now, see how I've anchored you?" I'm confused. "Why, because I said 'yes'?" "No, you didn't even notice. Every time you said 'yes', I touched this milk jug [on the table]. So, if I want to extract a 'yes' out of you, I touch the jug right before I ask a question. People who use these techniques are called 'hidden persuaders' – they decide what jumper, what watch, what shoes you wear.

"They've been in advertising for years, and in politics. For the first 11 days in office, President Obama wore a blue tie so that he was emotionally attached to people. When he wanted to display power during a speech, he wore a red tie. I don't think they [politicians] use these techniques in Ireland. Maybe they should."

In his downtime, Keith reads most people he encounters; partly for fun and partly to hone his skills. Charming though he may be, he is a no-nonsense man to interview, and he always has been. Add to this the possibility that you are being 'read', and talking to him can be a mildly disconcerting experience.

"If I'm in an airport, at the bar, I'll look at the fella next to me and I'll reckon he's, say, an accountant going through a divorce. I'll have a conversation with him to see if I'm right. More often than not, you get it right."

What about seducing someone or getting someone to fall in love with you through 'hidden persuasion'? "I don't think you can make that happen," Keith replies. "I've read [pick-up manual] 'The Game', where there are all these techniques to pull women. But it always ends in disaster.

"You can't make love happen. If you're doing seduction under false pretences, you're f*****."

He also lets psychics have it with both barrels, even though 'cold reading' and deduction is very much part of their shtick, too. "You know what?" says Keith, suddenly fired up. "I took a photo today of a woman who has spent €190,000 on psychics. With me, I'm clearly an entertainer. I'm not pretending to contact the dead or predict your future.

"Psychics prey on the vulnerable of society. They look like they're contacting the other side, but they're not, and they're interfering with the natural grieving process that everyone has to go through. The thing is, if you're a believer, you're a believer. I saw a psychic live recently and I left halfway through as I was so sick at how people were being deceived.

"The thing is, I know what I do is entertainment, pure hokum. But a psychic will swear that it's real when I know it's pure nonsense."

Either way, his 'hokum' has made for televisual gold, as watching people forgetting their own name or slapping their own faces might well be.

"Like, with a card trick, you know I'm doing something sneaky with my hands, but if I can hack into your brain, well, it's supposed to be the safest place for you in the world," Keith tells me. "You become vulnerable when it's not safe. But for entertainment purposes, it's kind of fun." He thinks for a second. "Yeah, it's kind of creepy too, I suppose."

'Brain Hacker' is a noted move away from the more daredevil feats he has undertaken. I ask if this is a conscious decision after he famously passed out on the Olympia stage during an '8 Deadly Sins' live show in 2012.

"I've had loads of accidents that never got reported in the press," he shrugs. "I've had dislocated thumbs, toes. I've lost a bean down my ear canal."

That fateful evening on the Olympia stage, however, was a different matter. The problems started when Keith unwittingly invited a professional sailor to tie him up in ropes as part of an escape act. Alas, the sailor did a rather stellar job.

Recalling the incident, he says: "People thought it was part of the act. Normally I don't panic, but that night I did. I sucked the clingfilm [that had been wrapped around his head as part of the feat]. The safety measure was the lads pulling me offstage, taking the clingfilm off my face and hoping that I hadn't been knocked out for too long. If ever I'm limp for more than 10 seconds, out they come."

Proving himself a consummate showman, he adds: "I knew one night it would fail, which is why I put that trick at the end – so the crowd would still get their two-hour performance."

Keith's celebrity pals also go by the wayside in his latest show. Previously, he has wowed Justin Timberlake and driven blindfolded with a terrified Nicole Scherzinger next to him. But this time round, the brain hackery itself is front and centre.

"The thing about celebs is that they're in control of their lives morning noon and night, with publicists coming out of their arses," he says.

"When you take one of them on a blindfolded drive, their reactions are real and they have no control. They're not putting it on for the camera. Hey, it's fun to hack into Matthew McConaughey's brain when he's drunk, messing him up."

When asked if there's anyone famous left to spook, he adds: "I'd love to work with Bono, actually. I've asked him a lot over the years, and he says he will, but it hasn't happened."

After spending much of his adolescence hanging around Dublin's Kitchen nightclub and fraternising on the edges of celebrity for decades, how does he feel about the concept of stardom in relation to him?

"I'm very lucky in Ireland that I can fill venues and keep my private life private," he says. "I get annoyed when I hear celebrities talk about being recognised, running from the cameras, all that. You came into this business knowing you'd be recognised, so don't moan about it when it happens."

Keith is currently filming a light entertainment show for the UK. But he has also presented the Irish version of 'Deal Or No Deal' and even popped up in 'CSI: Miami'. All of which suggests that his career interests may well lie beyond magic.

"I found presenting okay, but with acting I was way out of my comfort zone," he admits. "But the opportunity came my way and I took it."

Predictably, he lets his intuition take the reins when it comes to making career decisions: "I only do 'yes' or 'no'. When you over-think things, well, that's when you screw it all up."

• 'Brain Hacker' is on TV3 on Sundays at 9pm. Info on Keith's upcoming nationwide tour can be found at keithbarry.com