Card Tricks > Geometric Treatment Card Trick
Bewitched Switch (Which is Which?)
In the next trick, three playing cards are treated as three labeled
objects of identical design could have been used, playing cards are
possibly to be preferred, since they are similar and distinguishable
when viewed from the back, but quite different when viewed from the
front.
This mind-reading stunt is not only entertaining in its own right, but
also represents a baffling exercise in logic.
Presentation
The performer places three cards face down on a table in a row at
position 1, 2, and 3. A spectator is asked to make a note of these
positions. The performer then turn his back and request the spectator to
pick up one of the cards, memorise it, and replace it face down
at its original position.
The performer announces that he will attempt to identify the selected
card but to render the trick more difficult he proposes that the
spectator switch the cards about, but with the stipulation that this be
done only by switching two cards at a time and that the positions of the
switched cards be called out to the performer each time. To illustrate
the switching technique, the performer requests the spectator to try his
hand at this by first switching the two cards he did not pick up at the
beginning. For this trial switch, the spectator does not, of course,
give the positions of these two cards, since this would at one tip off
the performer to the position of the spectator's memorised card.
After several switches have been completed to the satisfaction of the
spectator, the performer turns towards the tabled cards and identifies
the card that the spectator originally picked up and memorised.
Method
Although the three face down cards superficially appear to have
identical backs, a closer inspection will usually reveal one card to
exhibit some minor difference such as crease, bend, flaw, nick, or other
imperfection. With new cards, some microscopic identifying mark may
become necessary such as a pencil dot, a fingernail indentation, or the
like. One of the cards need be marked and identified in this manner.
The performer, before turning his back on the proceedings, notes the
position of this marked card in the three card row on the table.
Thereafter, he must keep exact track of this card as the card are
switched from place to place. He can do this mechanically by using
the first three fingers of one hand. For example, if the marked card is
initially at position two, his thumb contacts his second finger. If a
switch is now made of the cards at positions 1 and 3, he does nothing
for his card at the number 2 positions is not involved. On the other
hand, if the switch involves the cards at position 2 and 3, he moves his
thumb from his second to third finger to indicate the new location of
his marked card.
With the completion of the switching routine, the performer turns to
face the tabled cards and notes the position of his marked card.
For example, if the performer's marked card is at position 2 and his
finger contacts indicates it should be at position 1, then the
spectator's memorised card is at position 3.
Explanation
The card that the spectator initially picks up for identification and
memorising can either be, or not be the same as the performer's marked
card.
- If the spectator picks the performer's marked card for his card
also, then the initial trial switch of the two other card leaves
this common card unchanged as to position. The tip off as to when
this event happens is given when the performer turns and observes
that the actual table position of his marked card corresponds to his
fingered position for this card at the end of the overall switching
routine.
- If the spectator selects a card for memorisation that is other
than the performer's marked card, then the performer's marked card
and the other card that the spectator did not pick up for
identification are the two cards that are switched at the very
beginning. This throws the performer's card out of position and puts
this third card in the spot vacated by the marked card.
- At the end of the switching routine, the performer turns to the
table and observes that his marked card is not where it should be as
indicated by the posting for this card on his fingers. This
immediately tips him off to the fact that his marked card and the
third indifferent card must have been switched in the initial trial
switch.
Comments
In working this card effect, it actually makes no difference at what
point the two cards, not initially selected by the spectator are
switched. But, the idea of a trial switch at the beginning is less apt
to be questioned by the spectator. An elegant adaptation of this three
card effect has been worked out that eliminates any need for the
performer to ever view the three card set up. However, it does call for
the cards to be returned to their original positions at the end of the
switching procedure.
Card Tricks > Geometric Treatment Card Trick
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