Sunday, 13 September 2009

Derren Brown, purveyor of bad science

Derren Brown is a brilliant entertainer. He captivated much of the nation last week when he appeared to predict Wednesday's national lottery result. The country was abuzz with speculation about how he'd achieved the feat and we eagerly awaited his Friday-night show where he promised to reveal all. But rather than explaining how he'd performed Wednesday's illusion, Brown committed a disservice to the public understanding of psychology. He invoked a real, fascinating phenomenon in social psychology - the so-called "wisdom of crowds" - distorted it, and half-baked it with flim flam about "automatic writing" and "deep maths".

The wisdom of crowds is the consistent finding that the averaged judgements of a diverse group of independent people will nearly always be more accurate than any single person's judgement, no matter how expert that individual is. Note the emboldened words. The group must be diverse, with members having unique insights into the problem at hand. Group members must also be independent, in the sense that their own judgement is not contaminated or swayed by the opinions of others. In these conditions, the combined, diverse knowledge of a group of people can be effectively brought to bear on a problem. Judgements biased in one direction will be cancelled out by judgements biased in the other direction, as the group's combined verdict homes in on the truth.

As described by James Surowiecki in his excellent book, stock exchanges provide an ideal, though imperfect, medium for the collective pooling of wisdom as many thousands of individuals place their judgements on future outcomes. Stock exchanges often arrive at highly accurate judgements, both trivial as in the Hollywood Stock Exchange, and more serious, as in the share market's prediction of who was to blame for the Challenger space disaster.

There's also a fascinating literature on why crowds often work badly, rather than fulfilling their potential for wisdom. In group meetings, for example, research shows that people have an unfortunate tendency to talk about the information that they share, thereby undermining the diversity of knowledge in the group. Similarly, social dynamics can lead to diseases of the crowd such as "group think", in which the pursuit of consensus undermines the very independence of each individual's input that is so vital for the wisdom of the crowd to emerge.

Other new exciting research in this field suggests that individuals may be able to exploit the principles of the wisdom of the crowd on their own, by making repeated, independent judgements and averaging them.

Returning to Derren Brown's lottery explanation, we can see that the wisdom of crowds has no use for predicting the lottery. His group of 24 individuals did not have diverse insight into what numbers will come next. The history of lottery results has no bearing on each successive draw, so there was no purpose in the group studying the archives of past results. Even if past results did affect future results, the 24 individuals sat staring at the same data. They didn't each bring their own unique knowledge to the table. Moreover, if Brown had really wanted to exploit the wisdom of crowds, he ought to have kept the members of his group separate so as to maintain their independence and prevent them biasing each others' input. And finally, why on earth would he have had a group of just 24 people? With so much at stake, if there had been any sense in attempting to pool the collective wisdom on this challenge (which there wasn't), Brown should have exploited the combined wisdom of as many people as he possibly could.

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These are the views of the Digest editor, not the British Psychological Society.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

16 comments:

  1. He is magician and a conjurer! He is a showman!

    Did you believe the mouse was really under cup 13? The cup would have moved if it had been, for example. No, Mr Brown palmed it in there when that was the last cup standing. Of course there was never a knife. I would have asked Mr Brown for a % of his fee for pretending to think there could possibly be one. (Rather than a cheque in case my foot was injured)

    My personal belief is that he had an inject printer in the stand for the balls - but what do I know?!

    One thing we do know is that Mr Brown is not going to reveal his secrets!

    But good luck to him.

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  2. To be fair, I think anyone with half a neurone realized immediately that the Wisdom of Crowds explanation was taking the piss. When you think about it, it's obviously ridiculous.

    How did he do it? My money is on some kind of broadcast delay. He has denied this, but, I don't trust him.

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  3. The author seems to have missed the whole point of Derren's show. He actually discounted the whole Wisdom of Crowds part towards the end when he came to the alternative of "manipulating the draw". He sneakily asked people to invoke Occam's Razor,i.e. that the manipulation is more plausible than the Wisdom of Crowds fad.

    Similarly, on his recent "The System", when he explained the fallacy of basing one's judgment to much on ones own point of view, he mentioned phenomena like homeopathy just in one sentence - instilling that eyewitness accounts and anecdotal evidence is not enough.

    To be fair, one has to use Occam's Razor once more regarding the lottery trick - the true trick is even simpler and more plausible than manipulating the draw...

    In summary, Derren is not only a showman and magician. More than anything he is someone who continuously challenges biases and pseudoscientific beliefs through his role as an entertainer - just not so "in your face" as some other skeptics and scientists.

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  4. @Neuroskeptic: Not a broadcast delay, but the very same camera trick they used in the ads for The Events where he juggles balls with his right hand. It's not his hand.

    Also, as an afterthought: The whole lottery show was about showing people that they believed in something that is not there at all. A mouse. A knife. A system to beat the lottery. One has just to make one step back and look at what he actually showed in that hour.

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  5. Derren gave us three options during the show, wisdom of crowds was option 2.
    Derren only discredited option 1 so if you are correct, that can only leave option 3, fix the lottery machine.
    You can read my post about option 3 at http://www.higgypop.co.uk/blog/post/652/

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  6. Anonymous10:20 am

    hmm. maybe it also leaves option 4? Or option 5? Or options 6-99?
    IT'S JUST A TRICK!

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  7. Paul Hutton2:21 pm

    I think Digest is being a bit hard on Brown (albeit for perfectly understandable reasons).

    First of all, Brown clearly states at the beginning of every show that he is going to try to pull the wool over our eyes (those who are angry at Brown forget this premiss). Secondly, he is not morally obliged to be truthful to us anyway - he is an entertainer not a scientist (he probably provokes scorn from scientists because he deliberately presents himself as trustworthy and thoughtful - but note my first point).

    It should be clear to most people after some thought that the wisdom of the crowds explanation has a much lower probability of being true than the alternative; that Derren Brown used psychology, misdirection and showmanship to deliberately mislead some people into thinking - just for a second - that there might be some truth in the bizarre claims he was making and that he didn't employ an altogether more mundane approach.

    The profound usefulness of Brown's approach to educating people about the benefits of scepticism is quite clear to me. First of all, he gets the attention of people who may find traditional science unexciting and alienating. Secondly, those who accept the wisdom of the crowds explanation will soon be ashamed to admit it as the gathering consensus becomes clear. They may ask: "how was I fooled so easily?". In their search for an answer they are likely to become 'inoculated' against the approaches of less ethical performers, conjurers, homeopaths, snake-oil salespeople and religious leaders. They may even start to become fans of science.

    There is an immense irony in his choosing the 'wisdom of the crowds' as an explanation. He has not misled us at all; in the chorus of disapproval that followed his bizarre explanation we find the 'wisdom of the crowds' phenomenon in full swing.

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  8. The fascinating aspect of the 'reveal' show to me was the reaction of the group that had supposedly put together the prediction. They were convinced that they had actually predicted all six numbers (assuming they were not just room full of actors which is the other plausible explanation). I would think that all of them would have discounted the possiblity of predicting the lottery numbers in such a fashion before the charade he pulled to make them think that they could. Similarly, in The System he persuaded a woman to part with £5,000 in a bet that she thought was a sure fire winner as he had tipped the winner of five other horse races. Her faith in The System was absolute, as those who had 'predicted the lottery' had faith in their new found ability to predict the impossible (or at least very unlikely). That tells us something about human gullibility and, if there is a point to his material other than pure entertainment, I would say that that was it. I think provides an intriguing insight into the origins of superstition and religion.

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  9. Anonymous8:12 pm

    As a devotee of roulette and the lottery, I can warrant that the odds of any combination of six numbers out of a possible 36 or 49 turning up together are well in to the millions (14 million in the case of the lottery). You only have to be there when they turn up. That's all. You just have to be there for about 10 million consecutive spins of the roulette wheel (they average about 30 an hour or less) so you'd need to spend quite a bit of consecutive time there (about 300,000 hours which suggests you may need a partner or even a team). Slight problem is there never could be 10 million consecutive spins because the Casino closes for a while every 24 hours. Similarly you could use your 6 favourite lottery numbers faithfully twice a week and the chances are they really WILL turn up altogether sometime. Meaning once every 14 million draws. Quite possble if you have some Rip Van Winkle in your DNA. Yes, those six numbers from Wednesday's draw really WILL all turn up together. They may even turn up together after as few as five million draws. On the other hand it may take 20 million. But predict they will turn up LAST WEDNESDAY is a bit of a punt isnt it?
    I agree with everyone who says Darren is challenging you to see if he can make a fool of you, and that's a worthy objective in itself. He's even polite enough to tell us that's what he's doing. And helpful enough to provide obviously crap explanations. I believe split screen is the current favourite!
    Sorry to be anonymous but if my family knew I was spending so much time in the Casino my life wouldn't be worth living.

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  10. I understand that Brown is an entertainer first and foremost and that he doesn't hide the fact that his purpose is to deceive, however, I can't help but feel quite uncomfortable about the gullible people out there who may well waste a lot of time, energy, and money trying to emulate what he did. You might assume that no-one could ever fall for it but I worked in a shop for a few years before I started university and you wouldn't believe some of the things I saw the hardcore gamblers try!
    Bit irresponsible of Brown but I still find him fun to watch I've got to say.

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  11. Way too much over analysis..

    The Reveal show was just massive misdirection this was blatantly obvious right from the start. Games with the audience that have no influence on what turned out to be no more than a mere illusion.

    The cup game with the mouse.. What type of person do you think he is going to use? I would hazard an intuitive guess - someone lacking in consciousness, someone easily manipulated just like everyone else he works with (cold reads). I would also say the mouse was never there in the first, he simply used distraction to preoccupy his subject and place the mouse there whilst his guest was most likely still preoccupied with amazement by what had just happened.

    As for the numbers game, notice how the last batch of so called calculations would be done by him, he then doesn't bother to show anyone the numbers, he simple pops a couple of balls in a plastic tube and says "Right, these are the numbers I'm off".. Leaving the participants in a high emotional state.

    Off he trundles to the live TV feed where he explains what he's doing to the viewers in a rushed manner, but he forgets one thing.. What's that Derren? Your not going to display your predictions on screen before the actual draw? Oh OK.. You can show me 'after' the actual results.. Which is exactly what he does, the rest in that short time space is merely am illusion where he displays the correct numbers on the balls when the plinth is turned around. How he does that bit is an illusion, but could be considered nothing more extrovert than what illusionists from the Victorian times were performing.

    Publicity stunt?
    What happened Derren you used to be great.. Regardless, looking forward to the rest of the series. Good viewing. Even better live apparently.

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  12. "Oh OK.. You can show me 'after' the actual results" - Yes - key point peachman - why did he not show his prediction before - that would have been stunning showmanship!!

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  13. The guy's a fraud. I bet you he can't even read minds!

    Seriously, I was disappointed by the 'reveal' programme at the time. But reading all the commentary afterwards makes me realise it was rather excellent TV.

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  14. 'The guy's a fraud. I bet you he can't even read minds!'

    derren brown doesnt claim to read minds, if that is what your implying Tom? he uses a variety of techniques (too many to mention) in mis-directing and manipulating peoples train of thought so they ultimately fall into his thinking traps. it doesnt always work on everyone. you can usually get a sense of this upon first meeting somebody. But that's by the by. what do you ean he is a fraud? his last words at the end of the show was that he will always claim this stunt was a 'trick'. and thats exactly what it is. a trick. derren brown is always honest in his dishonesty when it comes down to it.

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  15. derren brown is certainly not a purveyor of bad science.

    On the contrary, he raises awareness on many aspects of pseudo-science - paranormal concepts, alternative medicine etc. that’s what grabbed my attention and greatly elevated my impression of Derren Brown. Skepticism and critical thinking can’t be promoted enough.

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  16. Anonymous12:13 pm

    split camera, you can see the ball jump.


    I was hoping for more in his show than a 'wisdom of the crowds' but have to say he's a wonderful showman and I look forward to his new series next year

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