The Serial Effect
by Ben Highway

Effect: The performer borrows a tenner which its lender holds on to. At this point most might expect the performer to divine the serial number: but he doesn’t. Instead it is the participant who begins calling out letters and numbers which are jotted down. Incredibly enough upon comparing the two it is seen that they have, with near-perfect accuracy, managed to divine the serial number of their own note – and what’s more they are clueless as to how they managed to do it!

Insight: Students of cognitive psychology will be one ahead here: the clue is in the title. The Serial Position Effect is a term which refers to how the placing of a piece of information within a string of data affects recall of it. Namely: information at the beginning and the end of the list is more likely to be remembered than that in the middle.

Why this is important will become clear in a moment.

Required: You will need a note which is common to your locale and a spiral-bound notebook (the pocket-sized ones are ideal for this) replete with front and back cover.

As well as this you will require a pen, preferably soft-tipped.

Preparation: Open up your notebook and on the first page write the sequence that the serial number on your note takes - in the case of an English note:

Two letters
Eight numbers

Turn to the next page and rewrite the information, ensuring that there is at least some similarity between the two. If you wrote on the first page with a biro then you may follow and use the indentations it made as a guide.

Now all that is left to do is write down the serial number of your note on the first page. It is important that you do not make an indentation of it on the page beneath however, so either place something between them to prevent this from happening or write with a soft-tipped pen as per the above suggestion.

The serial position effect states that we are more likely to remember the information at the beginning and an end of a string of data. Thus we leave out the first and last digits (and one in the middle, for good measure) - these will be filled in during the performance with the participant’s actual numbers:

C4218 963

It is worthwhile searching for a note which has many different numbers on it - if there were five threes for instance then it becomes a little bit obvious for you would remember if you said ‘three’ five times.

Close the pad up and put it away in your pocket along with the note and pen. With those actions, you are ready to perform.

Performance: Enquire of your audience whether anybody possesses a note (which matches the one you have in your pocket). If you receive one then secretly switch it for yours.

Snap the note before your participant’s face before folding it up into a small package and handing it to them to hold on to.

“There is a reason we use money in this demonstration. Money is, on some level, important to most of us. The ten pounds you hold for instance is not an insignificant amount of money. It means something to you, and you’ve handled that note when you received it and when you’ve put it away in your wallet/purse as well as just now. What I find fascinating is how much information we can take in about these kinds of things without even realising it.”

This sets up the revelation and gives some rationale for how what happens happened. But because we don’t want to risk giving away the ending too early (if people knew they were going to try and determine the serial number of their note they would pay more attention to the data the participant is about to call out) we employ that marvellous word “but” to negate what we have just said:

“But first we are going to play a game of Countdown - you know where contestants get to choose letters and numbers and then they have to try and make something out of their choices. That is what is going to happen here and just like in the television show if you do well enough you get to win a prize: ten pounds..."

This last bit about the prize is naturally said tongue-in-cheek.

“This game, much like Countdown, does have rules however; I have them here somewhere...”

As you say this you fish out your notebook. You need to turn to the second page without making people aware of the fact that this is not the first page of the book. This is easily done by lifting up the front cover and the first page at the end of the pad nearest to you (like you might have caught a double with a pack of cards when you began in card magic - I know you did at some point) and revolve all of the pad beneath it over and on to the top cover. Angling the pad so that everybody can see what is written on the second (supposedly first) page you point out that they are to say two letters followed by eight numbers.

You close the pad by reversing the actions you made to open it before realising that it might be easier if you wrote down what they said. This time however you open the pad in the conventional way to the first page without letting anybody else see what is written on it.

“It’s important that you say this without really thinking about what you are going to say. Whatever two letters and eight numbers come into your head just say them. Try and get a nice range though, but don’t consciously think about it. Okay? Excellent. Thirty seconds on the clock... Go!”

This is suggestive of an intuitive approach, but in reality we do not want them paying too much attention to what they say because we’re about to show them a largely different string of data and attempt to pass it off as what they said.

So you write down what they say where applicable (I.e. in three instances) and mime the rest. For the last digit you tilt the pad down so that your participant (and rest of audience) can see it too. This is okay because you really write down what they say, and what is nice is that when calling out the data your participant probably won’t be focussing on the pad (eye accessing cues and all that)! So the image they see when they finish and look at the pad implies that you have been holding it like this the entire time, in which case you can’t have done anything funny because they (and/or the audience) would have seen you! You may also say:

“Now the last number, again take a moment - what do you want it to be?”

The word “again” of course implies that they were thinking carefully about their other choices, thus making it all seem very fair indeed.

Deliberately write whatever number they say in and drop the pad onto the table.

“I said that this was like a game of Countdown and it is in the sense that you were trying to structure something of relevance as well. As you well know our money has a serial number. And that serial number takes the form of two letters - and one number (you point to what is written on the pad as you say this). That ten pound note of yours you must have handled a fair bit, when you received it and sorted out your wallet/purse and all of that. So let's see how much of it you really did take in on a subconscious level...”

And go into the reveal! Often where you wrote down what they said if they didn't get it spot on then what they did say will likely be close in either proximity or appearance. Of course at the end you congratulate them and say that that was more than well enough etc.

Also when talking about writing down what they say it's best to use inclusive words such as "we" which makes things very fair and open.

Other options for the ‘closing up and revelation’ patter include:

“Thank you. It’s okay, you can relax now. And those were things that just came to you, without any... right, it was quite a subconscious approach to it all. Excellent, that's just what we needed..."

This is to take their mind off the letters and numbers - we associate them with a state of tension and so by changing that state (into one of relaxation) we move attention away from what they have just said. They will likely remember the first and last letters, but we have that covered.

We continue by beginning to suggest that they wrote down the numbers themselves:

“If you take a look at what you said and wrote down and then just look at the serial number on the note...”

It’s important that they re-familiarise themselves with ‘what they wrote down’ first of all because then when they look at the bill they see, pretty much, that same sequence (contrast this with the other approach in which they look at the bill first and see a bunch of meaningless data before looking at the serial number - the former approach is the stronger I think you will agree).

Avoid saying something like “Please re-familiarise yourself with what you said/wrote” because that implies that they will have forgotten what they put - which allows you some sneaky manoeuvring leeway. The strength of this is derived from the idea that they would realise if what is written is not what they said. In most instances of course this is completely untrue, but we let them become better acquainted with it before this doubt can form in their minds.

With Multiple Participants: When there is more than one person watching you can have someone else write down what your participant calls out. You ask them to “write it as neatly as possible” to make it as generic as possible, thus if the two people are participating are close friends they are unlikely to notice the discrepancy in the handwriting issue. Of course it is best to choose two people who seem as if they do not know one another and, if I may use another ‘of course’, you need to alter the preparation at the start, I.e. write the entire serial number on the first page and have your participant write down what is said on the next (second) page. Of course. When it comes to the reveal hand the pad to your first participant but then ‘realise’ that it may be a bit awkward if they were to read both so have them hand the note to the second participant and voila.

If You Cannot Borrow the Ten Pound Note: Simply use your own and adjust the patter line accordingly. If you do use the “prize” patter then make sure you let them keep the note at the end! Otherwise you are implying that they don’t get to keep the note because they didn’t do well enough!

With thanks to Iain Dunford.

Ben Highway