# When a Mentalist or Sherlock Holmes "read" someone **URL:** \ **Category:** Factual Questions\ **Created:** [February 20, 2015, 3:20am UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160 "2015-02-20T03:20:46Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 24, 2015, 3:26pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/61 "2015-02-24T15:26:18Z")
I mean he could have said something like “Pick a random number. Now reverse the digits of that number, and subtract the smaller from the larger”, and so on through steps like that. Even though the original number picked was random, they’ll all end up converging on the same number (and of course, he knows in advance what that number will be). Did he do this? I don’t know, because your initial description wasn’t clear enough to rule it out. Now you’re saying that you did it without any interference from him, but is that an accurate memory? Maybe, maybe not. Maybe what you actually remembered was “no significant interference”, because you didn’t think the interference was significant (but it was), and then your memory edited that down to “no interference”. There are probably dozens of different ways he could have done this trick, and if we listed them all one at a time, you’d probably say each time “No, he couldn’t have done it that way, because…”. And, meaning no aspersions against you, when you said that we wouldn’t believe you, because human memory really isn’t nearly as reliable as most of us think it is. ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 24, 2015, 3:36pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/62 "2015-02-24T15:36:27Z")
FTR, he didn’t say anything about picking a page number, or anything else about numbers (or pages). He said to pick a random word out of the book. If you’re willing to believe that we went through an extended process about page numbers and I completely forgot it and think he just said “pick any word out of the book”, you may as well go full monty and say I hallucinated or dreamt the whole thing. (That has the advantage of accounting for all his other tricks as well :).) ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [February 24, 2015, 3:50pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/63 "2015-02-24T15:50:38Z")
> [@Noel\_Prosequi](#): > > In reality, this is hopelessly unattainable. In reality, every single fact can, in principle, lead to a question which can lead to another fact in a sort of exponential explosion of detail. Not every rabbit can be chased down every burrow, and the satisfyingly closed universe of fictional clues yields to an untidy mass of details which can only be managed by corralling as much as seems necessary to make a pragmatic decision. Not every mystery needs to be explained or loose end tied off, nor in principle, can they be. Yep. And while we’re bashing Holmes\*, and just for the sake of completeness, the idea of “once you’ve eliminated the impossible, whatever remains, however improbable, must have happened” (or whatever the exact quote is) fails for similar reasons. In the real world, there is always the possibility that there’s another explanation that we have not thought of, _and_ it’s much more difficult to completely eliminate explanations. - Of course, he’s a fictional character, and I’m not dissing ACD. But rules of thumb like that do sometimes get quoted in discussions / debates as though they are actually useful. ---
**Author:** ![Kenm](https://avatars.discourse-cdn.com/v4/letter/k/bc79bd/32.png) [@Kenm](https://boards.straightdope.com/u/Kenm)\ **Post date:** [February 24, 2015, 4:24pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/64 "2015-02-24T16:24:34Z")
Stop the presses! An historian has unearthed [\*\*the first unseen Sherlock Holmes story in over 80 years \*\*](http://www.scotsman.com/lifestyle/heritage/historian-unearths-unseen-sherlock-holmes-story-1-3696749) which Sir Arthur Conan Doyle wrote to help save a town bridge. (The Scotsman newspaper.) Conan Doyle has Holmes smoking “a ton of tobacco” while staying up all night to figure out where Watson was off to the next day. Ha! ---
**Author:** ![Mk\_VII](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mk\_VII](https://boards.straightdope.com/u/Mk_VII)\ **Post date:** [February 24, 2015, 8:52pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/65 "2015-02-24T20:52:29Z")
Conan Doyle did turn detective in real life and took up the cudgels on behalf of several people who had, he thought, been wrongly convicted of crimes. ---
**Author:** ![Cartoonacy](https://avatars.discourse-cdn.com/v4/letter/c/848f3c/32.png) [@Cartoonacy](https://boards.straightdope.com/u/Cartoonacy)\ **Post date:** [February 24, 2015, 9:14pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/66 "2015-02-24T21:14:18Z")
If the book trick worked like [this](http://www.pubtricks.com/video-pub-anypageanyword-trick.html), then you can apparently find out how it’s done for $16.95. ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 24, 2015, 9:34pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/67 "2015-02-24T21:34:23Z")
More or less, except he didn’t do anything involving the page number or ask us to write anything down. He may (or may not) have asked us to concentrate on the word we chose. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [February 24, 2015, 11:20pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/68 "2015-02-24T23:20:32Z")
> [@Fotheringay-Phipps](#): > > None of this was done in the case I participated in. I flipped through the book and it was legit. The guy had offered to do it with any book that we produced, but the book he offered looked legit so we didn’t bother. (Someone else told me he had seen this same guy do it at a different party and in that case they gave give him a book of their own - in a foreign language.) How did you ascertain the book was legit by flipping through it? If, for example, it was the same 20 pages printed multiple times, how confident are you that you would have picked that up? Because of the way that people scan, so long as the construction of the paragraphs differs from page to page it can be almost impossible to detect this without spending at least 5 minutes reading the pages And this is exactly how forcing works. The magician offers to do anything, knowing full well that they will almost never need to. The audience remembers freely selecting the card/book/whatever when there never was any choice. And on those few occasions when someone does choose another book, then they use “outs”. For example, had you said that you wanted to use another book, then he would gently mock you for not trusting him, and call for 6 other volunteers from the audience to select books from a nearby bookshelf. He would then ask you to choose from one of those other books. Of course one of the volunteers is a plant who selected another appropriate book and he then uses forcing techniques to get you to select the correct book. Another common variant is that he magician asks you to choose a page and paragraph in your selected book, and then open the trick book to the same paragraph and page. One again, it seems like free will but there was never any choice. And what the audience remembers is that you chose a random book from the bookshelf. > [@](#): > > More or less, except he didn’t do anything involving the page number or ask us to write anything down. He may (or may not) have asked us to concentrate on the word we chose. The problem is that people are really bad at remembering what actually happened, and magicians make use of that by implying what they want the audience to remember and distracting from what they do not. As you have described this, the magician picked a random audience member, a random book, wasn’t watching when the page was selected, was able to perform the trick in a foreign language and the word was never written down. At this stage, it’s becoming hard to see how the trick could possibly be performed. There’s no apparent way that the magician could know the information. Even having an accomplice or hidden cameras on the room won’t help because the magician can’t know what words appeared on the selected page of a random book. I suspect that you have misremembered how the trick occurred, which is very common with people remembering these tricks. I’ve done it multiple times. This mostly occurs with instances of forcing. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [February 24, 2015, 11:52pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/69 "2015-02-24T23:52:48Z")
> [@Cartoonacy](#): > > If the book trick worked like [this](http://www.pubtricks.com/video-pub-anypageanyword-trick.html), then you can apparently find out how it’s done for $16.95. That is just a variation on a very common, old trick. They all rely on the magician writing down his answer after the subject has written their’s down. In this case, notice how the magician subtly forces the subject to write on cover of the subject book, which is then carefully “laid aside” before the magician writes his answer? There are a dozen ways this could be done. The inside of the front cover could be carbon paper, leaving an impression of what was written on it. Their could be a UV fluorescent version of carbon backing the post it note, which is read by an assistant who takes the book when it is cast aside. Or it could be any variation on the theme. Alternatively, the magician is surreptitiously writing the answer on his sheet of (blank) paper using a small pencil under his thumbnail after the subject reveals it by putting it in the bench. ---
**Author:** ![Isamu](https://avatars.discourse-cdn.com/v4/letter/i/7c8e57/32.png) [@Isamu](https://boards.straightdope.com/u/Isamu)\ **Post date:** [February 25, 2015, 7:26am UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/70 "2015-02-25T07:26:04Z")
> [@Archeonomist](#): > > Why would a hitman have manicured fingernails? Because he has plenty of free time since nobody really uses hitmen in real life. 🙂 ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 25, 2015, 4:26pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/71 "2015-02-25T16:26:44Z")
> [@Blake](#): > > How did you ascertain the book was legit by flipping through it? If, for example, it was the same 20 pages printed multiple times, how confident are you that you would have picked that up? Because of the way that people scan, so long as the construction of the paragraphs differs from page to page it can be almost impossible to detect this without spending at least 5 minutes reading the pages It’s theoretically possible that the book had some repeated pages. As you note, I only flipped through it glancing at snatches here and there. Not sure how much that gets you. > [@](#): > > And this is exactly how forcing works. The magician offers to do anything, knowing full well that they will almost never need to. The audience remembers freely selecting the card/book/whatever when there never was any choice. And on those few occasions when someone does choose another book, then they use “outs”. > > For example, had you said that you wanted to use another book, then he would gently mock you for not trusting him, and call for 6 other volunteers from the audience to select books from a nearby bookshelf. He would then ask you to choose from one of those other books. Of course one of the volunteers is a plant who selected another appropriate book and he then uses forcing techniques to get you to select the correct book. Another common variant is that he magician asks you to choose a page and paragraph in your selected book, and then open the trick book to the same paragraph and page. One again, it seems like free will but there was never any choice. As I said, someone present had seen another instance of the guy doing it with a book off the shelf. Although it did occur to me that he may have multiple ways of doing the trick and I don’t know the details of how he did it on that other occasion. > [@](#): > > The problem is that people are really bad at remembering what actually happened, and magicians make use of that by implying what they want the audience to remember and distracting from what they do not. Agreed. Absolutely. But there are things that you can forget and/or not notice and things that you won’t. The whole basis of many magic tricks is to have the audience not notice unimportant-seeming things that the magician is doing offhandedly while focusing the audience’s attention on unimportant but flashier actions. But if you’re going to suggest, for example (as Chronos did earlier) that a magician could have an extended back-and-forth involving the selection of the page number and have the guy he interacted with forget it entirely - WADR that does not hold water. I’m certainly willing to buy that he did something that I didn’t notice or forgot, but not a significant amount of interaction as that. > [@](#): > > As you have described this, the magician picked a random audience member, a random book, wasn’t watching when the page was selected, was able to perform the trick in a foreign language and the word was never written down. > > At this stage, it’s becoming hard to see how the trick could possibly be performed. There’s no apparent way that the magician could know the information. Even having an accomplice or hidden cameras on the room won’t help because the magician can’t know what words appeared on the selected page of a random book. Agreed. But you see, here’s the thing. There are a lot of clever tricks out there, and many of them are “hard to see” until you know how they were done. Then they frequently seem simple, but not until then. What you’re saying seems to boil down to “I’m familiar with only 3 ways the trick could have been performed, therefore it must have been done one of these three ways”. I don’t see that as compelling. FWIW, I should add a bit more detail that seems to slightly point in the direction of a “cold reading” technique. As I said earlier, he did a one or two sentence “mentalist” spiel before settling on the word “bartender”. In the course of that he did slightly emphasize a couple of other words that might be associated with bartenders (possibly “glass” and “ice”) and paused a bit, at which point I announced that it was neither of those words, and he continued on with something like “… as might be poured by someone like a _bartender_”, with emphasis on the final word. The thing was that neither of the two other words he may have been suggesting were actually on the page connected to the word “bartender” and in any event it seemed like a shot in the dark to have even guessed those words too. So I thought more likely he was playing it up for dramatics by seeming to guess wrong. But perhaps not. I was also struck by the fact that he had two people pick the word when one could have sufficed. So I thought most likely he was trying to force them to communicate somehow in agreeing on the word so he could pick up on it, e.g. get a glimpse of them as they pointed to the spot in the book where the word was. But again, we held up the book to our faces, and his back was to us until after we picked the word. (And it could be that he wanted two people so as for forestall some jerk from showing him up by lying about which word it was.) Possibly it was a combination of different techniques. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [February 25, 2015, 4:54pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/72 "2015-02-25T16:54:56Z")
Doing the trick with “a book off a shelf” may well have been an instance of forcing - where there were a number of books taken from a shelf, and the prepared book mixed in, possibly surreptitiously, and then the selection of the prepared book forced. Then it looks very much like a random book off a shelf was used. The pages on a prepared book don’t have to be the same. What likely matters is a set of mathematical relationships than can be reasonably calculated mentally that control the layout of the words. This relationship can include the page number. Or may be quite independent of the page number and relate to the entire order of the text. What we don’t know is the precise interchange that occurred. One assumes it was not “open the book at a random page, pick a word. OK the word is - bartender.” Did you answer anything at all? Did you get any instruction other than pick a word? It is impressive how much you can write using a vocabulary [of only 1000 words](http://xkcd.com/1133/). You only need ten bits of information to reference one in a thousand. Whilst you were not playing “ten questions” it is possible that every action was in effect cutting the search space down a few bits at a time. Three actions with modulo 10 arithmetic as their core might be enough. The book may use a lot less than 1000 words and still look quite plausible. ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 25, 2015, 5:03pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/73 "2015-02-25T17:03:04Z")
> [@Francis\_Vaughan](#): > > Doing the trick with “a book off a shelf” may well have been an instance of forcing - where there were a number of books taken from a shelf, and the prepared book mixed in, possibly surreptitiously, and then the selection of the prepared book forced. Then it looks very much like a random book off a shelf was used. But the guy who lives there would know that he doesn’t own that book. > [@](#): > > The pages on a prepared book don’t have to be the same. What likely matters is a set of mathematical relationships than can be reasonably calculated mentally that control the layout of the words. This relationship can include the page number. Or may be quite independent of the page number and relate to the entire order of the text. What we don’t know is the precise interchange that occurred. One assumes it was not “open the book at a random page, pick a word. OK the word is - bartender.” Did you answer anything at all? Did you get any instruction other than pick a word? There were definitely no questions or interaction. It’s possible that he may have said not to use words like “and” or “the” (I don’t specifically recall this, but it’s possible). He also may have said that we should think of the word so as to allow him to do his telepathy shtick (this was early in the show when he was giving a veneer of telepathy to it - but he wasn’t taking it very seriously even then, and later in the show he dropped the pretense altogether). I’m absolutely sure there was no give-and-take relating to the word itself. (I was very focused on whether and how he would be able to do it, and I would not misremember something like that.) ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [February 25, 2015, 5:20pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/74 "2015-02-25T17:20:41Z")
> [@Fotheringay-Phipps](#): > > **But the guy who lives there would know that he doesn’t own that book.** > There were definitely no questions or interaction. It’s possible that he may have said not to use words like “and” or “the” (I don’t specifically recall this, but it’s possible). He also may have said that we should think of the word so as to allow him to do his telepathy shtick (this was early in the show when he was giving a veneer of telepathy to it - but he wasn’t taking it very seriously even then, and later in the show he dropped the pretense altogether). > > I’m absolutely sure there was no give-and-take relating to the word itself. (I was very focused on whether and how he would be able to do it, and I would not misremember something like that.) But the guy who lives there could have been in on it. His wife did hire the “mentalist” for the party, and that would make it more entertaining for the rest of the guests. ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 25, 2015, 5:23pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/75 "2015-02-25T17:23:55Z")
To be clear: the party I was at was the one where the wife hired the mentalist. At that party we used the book offered by the mentalist. One guest at that party had been at a different party with the same mentalist where the subjects had chosen a book off the shelf. I don’t know the details of what was done at that other party. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [February 25, 2015, 6:05pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/76 "2015-02-25T18:05:12Z")
Wild guess: > [@](#): > > He was hoping to have enough time later to go > to the gym. He was an avid weightlifter and run- > ner. In his off hours he liked to check out the local > haunts. When he was a bartender, he always > worked out after the shift. ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 25, 2015, 6:16pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/77 "2015-02-25T18:16:09Z")
It’s possible. The word placement was approximately the same as it is in the [book you refer to](http://www.marketplaceofthemind.com/pdf/MOABT-PEBrochure(6pages).pdf). So how does that book work? ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [February 25, 2015, 6:17pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/78 "2015-02-25T18:17:46Z")
> **[Book test](https://en.wikipedia.org/wiki/Book_test)** > > The book test is a classic mentalism demonstration used by mentalists to demonstrate telepathy-like effects. The name refers to its early use as a test of mental powers. > An audience member (the "spectator") is called onstage to assist the mentalist. The spectator is shown one or more books, and asked to read a random passage from one of them. The passage may be revealed to the audience, or recorded in some other way for later comparison. The mentalist then typically presents a routine to establi... ---
**Author:** ![Fotheringay-Phipps](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@Fotheringay-Phipps](https://boards.straightdope.com/u/Fotheringay-Phipps)\ **Post date:** [February 25, 2015, 6:23pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/79 "2015-02-25T18:23:35Z")
That’s just a loose description of various techniques. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [February 25, 2015, 6:25pm UTC](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160/80 "2015-02-25T18:25:59Z")
> [@](#): > > But the guy who lives there would know that he doesn’t own that book. So you make sure that the subset of people who get a chance to take a close look at the book doesn’t include the guy who lives there. > [@](#): > > To be clear: the party I was at was the one where the wife hired the mentalist. At that party we used the book offered by the mentalist. One guest at that party had been at a different party with the same mentalist where the subjects had chosen a book off the shelf. I don’t know the details of what was done at that other party. Well there you go, then. The simplest explanation then is that the mentalist had a trick book of some sort. This wouldn’t explain what the other guest supposedly saw, but it really doesn’t need to: By that point we’re dealing with hearsay with few details from a source of unknown reliability. By that point the question might as well be “I saw a magic trick once; how was it done?”. There are so many possible explanations that there’s no point even beginning to list them. [Previous page](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160.md?page=3) [Next page](https://boards.straightdope.com/t/when-a-mentalist-or-sherlock-holmes-read-someone/713160.md?page=5)