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Nature Reviews Neuroscience | AOP, published online 30 July 2008; doi:10.1038/nrn2473
PerSPectiveS
involve higherlevel cognitive functions,
Science and Society
such as attention and causal inference (most
coin and card tricks used by magicians fall
Attention and awareness in stage into this category).
The application of all these devices by
magic: turning tricks into research the expert magician gives the impression
of a ‘magical’ event that is impossible in the
physical realm (see TABLE 1 for a classifica
Stephen L. Macknik, Mac King, James Randi, Apollo Robbins, Teller, tion of the main types of magic effects and
John Thompson and Susana Martinez-Conde their underlying methods). This Perspective
addresses how cognitive and visual illusions
Abstract | Just as vision scientists study visual art and illusions to elucidate the are applied in magic, and their underlying
workings of the visual system, so too can cognitive scientists study cognitive neural mechanisms. We also discuss some of
illusions to elucidate the underpinnings of cognition. Magic shows are a the principles that have been developed by
manifestation of accomplished magic performers’ deep intuition for and magicians and pickpockets throughout the
centuries to manipulate awareness and atten
understanding of human attention and awareness. By studying magicians and their
tion, as well as their potential applications
techniques, neuroscientists can learn powerful methods to manipulate attention to research, especially in the study of the
and awareness in the laboratory. Such methods could be exploited to directly study brain mechanisms that underlie attention
the behavioural and neural basis of consciousness itself, for instance through the and awareness. This Perspective therefore
use of brain imaging and other neural recording techniques. seeks to inform the cognitive neuroscientist
that the techniques used by magicians can
be powerful and robust tools to take to the
Magic is one of the oldest and most wide powers. The devices used by magicians can laboratory. The study of the artistic intui
spread forms of performance art1 (FIG. 1). It is include one or more of the following: visual tions that magicians have developed about
also a discipline with a long legacy of infor illusions (afterimages), optical illusions attention and awareness might further lead
mal experimentation. This informal research (‘smoke and mirrors’), cognitive illusions to significant new scientific insights into
by magicians aims to determine what condi (inattentional blindness), special effects (explo their neural bases.
tions allow for the maximum manipulation sions, fake gunshots, et cetera), and secret
of human attention and perception. Much devices and mechanical artifacts (gimmicks). Visual illusions in magic
as early filmmakers experimented with Visual illusions — and other sensory Visual illusions are often used by neuro
editing techniques to determine which illusions — are phenomena in which the scientists to dissociate the neural activity
technique would communicate their intent subjective perception of a stimulus does not that matches the perception of a stimulus
most effectively, magicians have explored the match the physical reality of the stimulus. from the neuronal activity that matches the
techniques that most effectively divert atten Visual illusions occur because neural circuits physical reality. Those neurons, circuits and
tion or exploit the shortcomings of human in the brain amplify, suppress, converge brain areas with activity that matches the
vision and awareness. As such, magic is a and diverge visual information in a fashion physical stimulus rather than the subjective
rich and largely untapped source of insight that ultimately leaves the observer with a perception can be excluded from the neural
into perception and awareness. Insofar as the subjective perception that is different from correlates of consciousness. Visual illusions
understanding of behaviour and perception the reality. For example, lateral inhibitory are also used by magicians to fool their audi
goes, there are specific cases in which the circuits in the early visual system enhance ences, often to enhance cognitive illusions.
magician’s intuitive knowledge is superior to the contrast of edges and corners so that Here we discuss a few categories of visual
that of the neuroscientist. In this Perspective, these visual features seem to be more salient illusions that have contributed to magic
we underline potential areas in which neuro than they truly are2–6. Unlike visual illusions, tricks, as well as their neural bases.
scientists stand to reap great benefits from optical illusions do not result from brain
collaboration with the magic community processes: they manipulate the physical Spoon bending. In this illusion the magician
(BOX 1 highlights one such potential area of properties of light, such as reflection (using bends a spoon, apparently by using the
collaboration). mirrors) and refraction (a pencil looks power of the mind. In one part of the trick,
Using completely natural means, magi broken when it is placed upright in a glass the magician holds the spoon horizontally
cians create effects (magic tricks) that seem of water owing to the different refraction and shakes it up and down. This shows that
to be outside the laws of nature. One should indices of air and water). Cognitive illusions the neck of the spoon has apparently become
note that, unlike socalled psychics, magi can be distinguished from visual illusions flexible7. The apparent rubberiness of the
cians do not claim to possess supernatural in that they are not sensory in nature: they spoon is an example of the Dancing Bar
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PersPectives
on stage that consequently seems to both
expand and contract. Motion aftereffects,
more commonly known as The Waterfall
Illusion, are the oldestrecorded visual illu
sions. First reported in his Parva naturalia,
Aristotle noticed that if one fixates a moving
stream of water and then looks away, the
rocks at the side of the stream will seem to
move in the opposite direction to the water.
This effect is caused by neural adaptation —
that is, by the decrease in responsiveness of a
neural system to a constant stimulus. In the
Trizonal space Warp illusion, adaptation to
expanding and contracting motion occurs in
three different parts of the visual field.
The above illusions are examples of magic
tricks that could have been used to help
elucidate the underpinnings of visual per
ception. There might be other fundamental
visual processes that could be discovered by
studying magic (BOX 1). Further, we propose
that there are cognitive processes that will
be better understood as we learn more from
magicians, as discussed in the next section.
cognitive illusions in magic
Figure 1 | The conjurer, by Hieronymus Bosch. A magician performs for the crowd in medieval
europe, while pickpockets steal the spectators’ belongings. the paintingNature
is in the Musée| Neuroscience
Municipal in
Inattentional blindness and change blindness.
Reviews Attended objects can seem to be more salient
St.-Germain-en-Laye, France.
or to have higher contrast than unattended
objects19–22. These perceptual effects have
(or rubber Tree) illusion8, in which an woman is revealed to be actually wearing a welldocumented neural correlates in the
oscillating bar (or rubber tree) seems to red dress. Here is how it works: when the red visual system23. Magicians use the general
bend when it is bounced rapidly. The neural light shuts off there is a short period of dark term ‘misdirection’ to refer to the diversion
basis of this illusion lies in the fact that ness in which the audience is left with a brief of the spectator’s attention away from a
endstopped neurons (that is, neurons that positive afterimage of the reddressed (actu secret action. Thus, misdirection can be
respond both to motion and to the termina ally whitedressed but redlit) woman. This defined as drawing the audience’s attention
tions of a stimulus’ edges, such as corners short afterimage persists for enough time away from the ‘method’ (the secret behind
or the ends of lines) in the primary visual to allow the white dress to be rapidly the ‘effect’) and towards the effect (what the
cortex (area V1) and the middle temporal removed while the room is still dark. When spectator perceives)7,24. Misdirection can be
visual area (area MT, also known as area V5) the white lights come back, the red dress applied in an overt or a covert manner. Here
respond differently from nonendstopped that the assistant was always wearing below we use the term ‘overt misdirection’ to indi
neurons to oscillating stimuli8–11. This dif the white dress is now visible. cate cases in which the magician redirects
ferential response results in an apparent This same illusion is the basis for percep the spectator’s gaze away from the method.
spatial mislocalization between the ends of a tual stability during the viewing of motion In the more subtle ‘covert misdirection’, the
stimulus and its centre, making a solid object pictures (the image seems to be stable when magician draws the spectator’s attentional
look like it flexes in the middle. in fact it is flickering). On a neural level, spotlight (which can be thought of as the
both turning on and turning off a stimulus spectator’s focus of suspicion) away from the
The Retention-of-Vision Vanish. Persistence generate responses in visual neurons that method without redirecting the spectator’s
of vision is an effect in which an image result in the perceptual visibility of the gaze. Thus, in covert misdirection the spec
seems to persist for longer than its presenta stimulus15. The neural response that is tators can be looking directly at the method
tion time12–14. Thus, an object that has been generated by turning off a stimulus is called behind the trick and yet be unaware of it
removed from the visual field will still seem the after-discharge, and it has the perceptual because their attention is focused elsewhere.
to be visible for a short period of time. The consequence of a positive afterimage that The concept of covert misdirection is
Great Tomsoni’s (J.T.) Coloured Dress trick, persists for approximately 100 ms after the exemplified by the cognitiveneuroscience
in which the magician’s assistant’s white termination of the stimulus16–18. paradigms of change blindness and inat
dress instantaneously changes to a red dress, tentional blindness. With change blindness,
illustrates an application of this illusion to Jerry Andrus’s Trizonal Space Warp. In people fail to notice that something is differ
magic. At first the colour change seems to be this illusion the audience stares for several ent from the way it was before. This change
due (trivially) to the onset of red illumina seconds at a spinning disk with three zones can be expected or unexpected, but the key
tion of the woman. But after the red light is of expanding and contracting motion. They is that it requires the observer to compare
turned off and a white light is turned on, the are then asked to look at a different object the postchange state with the prechange
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Box 1 | Pickpockets pick your brain blinks, saccadic movements or how far the
cigarette was from the centre of vision at
One area of neuroscience research in which magicians might have stolen the show is the dynamic the time of the drop. The authors concluded
control of attentional focus. One of the authors of this Perspective (A.R.) is a professional thief, and that the magician primarily manipulates
he reports that as part of his formal (albeit illegal) training he was taught how to move his hands so
the spectators’ attention rather than their
as to draw the attention of his ‘mark’, or victim, in specific ways according to the particular
conditions of the robbery (see also Supplementary information S3 (movie)). Specifically,
gaze, using similar principles to those that
pickpockets move their hands in a curvilinear motion to misdirect the attention of the mark along are used in inattentionalblindness studies.
the curvilinear trajectory, whereas they move their hands in a fast linear fashion to invoke fast Thus, to overcome the magician’s misdirec
attentional shifts from one spatial location to another, which serves to reduce the strength of the tion, spectators should reallocate their
attentional focus. The neuroscientific underpinnings of these effects are unknown, but here we attention — rather than their gaze — to the
propose several possibilities that could be tested empirically. concealed event (that is, the cigarette drop)
One possibility is that these effects are due to differential engagement of the smooth pursuit and at the critical time36. recent studies have
saccadic oculomotor systems. The curvilinear motion could draw the mark’s oculomotor system found that the directions of microsaccades
into a long pursuit of the pickpocket’s wandering hand; the foveal centre of vision would then can also be used as an indicator of the spa
follow the length of the trajectory, presumably dragging the attentional spotlight along with it.
tial allocation of covert attention37–39. Future
The fast straight motion could invoke a saccadic eye movement, and the suppression of visual
perception that is known to occur during saccades91–93 might result in reduced attention.
research could aim to measure the micro
A second possibility is that, rather than the oculomotor system being differentially affected by saccade direction biases of spectators during
the two types of motion, curvilinear target motions might be perceptually more salient than linear successful and unsuccessful magic tricks.
target motions, irrespective of eye movements. Curves and the corners of object surfaces are A recent study of the VanishingBall
perceptually more salient and generate stronger neural activity than straight edges, possibly Illusion further supports the conclusion
owing to the fact that they are less redundant and predictable (and therefore more novel and that the manipulation of gaze position is not
informative)2–4. This decreased-redundancy argument might also apply to non-predictable critical for effective covert misdirection. In
object-motion trajectories. If this is the case, curvilinear motion trajectories should be more salient the VanishingBall Illusion, a ball thrown
(and consequently engage stronger attention) than straight trajectories. by the magician vanishes midflight. To
The above possibilities are not mutually exclusive. Further, it could also be that the pickpocket’s
achieve this effect, the magician begins by
intuition is incorrect, and that different motion trajectories do not differentially engage the
observer’s attention. Either way, the empirical assessment of these issues would lead to novel
tossing the ball straight up in the air and
scientific findings of potential significance. Thus, this subject is one of many into which catching it several times without event;
neuroscientists might gain insight from the study of magic. then, on the final toss, the magician only
pretends to throw the ball. The ball is in
reality hidden in the magician’s hand, but
state. Changeblindness studies have shown the scene and beats its chest!). In this situa most spectators perceive it ascending and
that dramatic changes in a visual scene will tion no acute interruption or distraction was then vanishing midflight. During the
go unnoticed if they occur during a transient necessary, as the assigned task of counting execution of this trick, the magician’s head
interruption25, such as a blink26, a saccadic passes was absorbing. Further, the observers and eyes follow the trajectory of an imagi
eye movement27 or a flicker of the scene28–31, had to keep their eyes on the scene at all nary ball being thrown upwards. Kuhn and
even when people are looking right at times in order to accurately perform the land40 found that the magician’s use of such
the changes. However, observers can also task. Memmert showed, using eyetracking social cues was critical for making the spec
miss large gradual changes in the absence recordings, that many observers did not tators’ perceive the illusion (that is, the ball
of interruptions32. A dramatic example of notice the gorilla even when they were vanishing midflight). However, observers
change blindness is illustrated in the Colour looking directly at it34. did not direct their gaze to the area in which
Changing Card Trick video by richard The magic community considers the they claimed to have seen the ball vanish,
Wiseman and colleagues (available online at covert form of misdirection to be more suggesting that the oculomotor system is
YouTube.com). In this demonstration, the elegant than the overt form7. Few studies not fooled by the illusion. Instead, the illu
viewers fail to notice colour changes that have addressed their relative efficacy, how sory effect is presumably caused by covert
take place offcamera. ever. Kuhn and Tatler35 measured the eye redirection of the attentional spotlight to the
With inattentional blindness, people fail movements of observers during the pres predicted position of the ball. This result is
to notice an unexpected object that is fully entation of a magic trick (a magician made consistent with previous studies that sug
visible in the display. Thus, inattentional a cigarette ‘disappear’ by dropping it below gested that there are separate mechanisms
blindness differs from change blindness in the table). To our knowledge, this is the first for perception and visuomotor control41–48.
that no memory comparison is needed — study to have correlated the perception of For instance, the eye movements of blindsight
the missed object is fully visible at a single magic with any physiological measurement. patients are biased towards stimuli that
point in time. In a classic example of inat The goal of the experiment was to analyse the patients do not consciously perceive49–51.
tentional blindness, simons and Chabris33 the scan paths of subjects to determine Kuhn and land40 further proposed that
asked observers to count how many times whether observers missed the trick because in the VanishingBall Illusion the covert
the members of a basketball team passed they did not look at it at the right time or redirection of the attentional spotlight to
a ball to one another, while ignoring the because they did not attend to it (irrespec the predicted position of the ball might be
passes made by members of a different team. tive of the position of their gaze). The related to “representational momentum”
While they concentrated on the counting results showed that the detection (or not) (REF. 52). That is, that the final position of a
task, most observers failed to notice a person of the cigarette drop could not be explained moving object that suddenly disappears is
wearing a gorilla suit walk across the scene at the level of the retina. That is, detection perceived further along the path of motion
(the gorilla even stops briefly at the centre of rates were not significantly influenced by than its actual final position. The neural
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correlates of representational momentum tricked by the strong implied motion that is implied motion (some examples of implied
might be located in the posterior parietal suggested by the magician’s moves. recent motion are the speed lines that are used by
cortex in the primate53. Observers of the studies have focused on the neuronal cartoonists, and still photographs of people
VanishingBall Illusion might also be mechanisms that underlie the perception of running or dancing). neurons that respond
table 1 | types of conjuring effects*
Magic effects examples Methodological strategies
Appearance: an Pulling a rabbit out of a hat; the Miser’s Dream • the object was already there but was concealed (for example, the magician
object appears ‘as (in which hundreds of coins seem to appear might conceal a coin in his or her hand prior to its production)
if by magic’ where previously there were none)75,94 • the object was secretly put into position (for example, in the cups and Balls
(BOX 2; Supplementary information S2 (movie)); routine, various objects are secretly loaded under the cups during the routine)
Mac King’s giant rock in a shoe trick75,87 • the object is not there but seems to be (for example, a ‘medium’ can simulate
(Supplementary information S3 (movie)) the presence of a spirit at a séance by secretly touching a spectator)
vanish: an object vanishing of a coin; Penn and teller’s • the object was not really where it appeared to be to begin with (for example,
disappears ‘as if by underwater vanishing of a naval submarine; the magician fakes a transfer of a coin from the left hand to the right hand,
magic’ David copperfield’s vanishing of the Statue of then shows that the coin ‘disappeared’ from the right)
Liberty • the object has been secretly removed (for example, the magician uses a
secret device, called a gimmick, to pull an object into his sleeve)
• the object is still there but is concealed (a coin can seem to vanish from the
magician’s hand although in reality it is merely concealed)
transposition: an Houdini’s Metamorphosis (in which two • the object seemed to be at A, but actually was already at B (for example,
object changes people change places between locked boxes); the magician fakes the transfer of a coin from the right to the left hand, then
position in space Penn and teller’s Hanging Man trick (in pretends to transfer the coin magically from left to right)
from position A to which Penn is apparently hanged to death, • the object is still at A but seems to be at B (for example, the magician fakes
position B only to be found safe and sound in the a coin transfer from the left hand to the right and then, when revealing the
audience) coin by dropping it, uses sleight of hand to give the impression that it was
dropped from the right hand)
• the object was secretly moved from A to B (for example, a coin in the left
hand is secretly transferred to the right hand and then is revealed there)
• A duplicate object is used (for example, both hands hold identical coins that
are revealed at different times to simulate a transfer)
restoration: an cutting and restoring a rope; sawing an • the object was not really damaged
object is damaged assistant in half; tearing and restoring a • the object was not really restored
and then restored newspaper; breaking and restoring rubber • A duplicate is used
to its original bands
condition
Penetration: chinese Linking rings (metal rings that link • Penetrations combine the techniques used in the transposition and
matter seems to and unlink magically); Houdini’s Walking restoration categories
magically move through a Wall trick; coins through the table
through matter
transformation: colour-changing card trick; Spellbound (in transformations can be seen as the vanishing of object A combined with the
an object changes which a coin turns into a different coin); the appearance of object B:
form (size, colour, Professor’s Nightmare (in which three ropes of
• Object A was secretly switched with object B
shape, weight, etc.) different length are made equal in length)
• Object B was always present but was initially disguised as object A
• Object A is disguised as object B at the point of ‘transformation’
extraordinary extraordinary memory (remembering the names • Might rely on relatively obscure scientific knowledge (such as mathematical
feats (including of all the audience members); extraordinary or physiological knowledge). For example, walking on hot coals is harmless
mental and calculation (reporting the result of multiplying when performed correctly
physical feats) randomly selected 4-digit numbers);
extraordinary strength; invulnerability
(specific examples: walking on hot coals; Penn
and teller’s bullet-catching trick)
telekinesis: Levitation; spoon bending • the action is caused by an external force (for example, an invisible thread)
‘magical’ levitation • the action is caused by an internal force (elasticity, chemical reaction,
or animation of an magnetism, etc.)
object • the action did not actually occur (for example, a spoon bender can convince
a spectator that a stationary spoon is still bending)
extrasensory clairvoyance (acquiring information that is • controlling a spectator’s choices to give the illusion of free will
perception not known to others through eSP); telepathy • Discovering hidden information (for example, reading information that
(eSP; including (acquiring information that is known to has been sealed in an envelope, fishing for or pumping information from a
clairvoyance, others through eSP); precognition (acquiring spectator, cold reading, etc.)
telepathy, information from the future); mental control • revealing apparent proof that information announced by the spectator
precognition, (the performer influences the selection was previously known by the magician (for example, by writing the
mental control, process of another person) announcement on paper and using sleight of hand to make the paper seem
etc.) to come out of an envelope that was sealed before the announcement)
*We adopt Lamont and Wiseman’s classification7 of conjuring or magic effects into nine main categories.
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to implied motion are found in extrastriate a subject to perform a task that involves Misdirection occurs not only in space
visual areas of the dorsal stream, and they one specific object, so that any changes (what the audience looks at) but also in time
are thought to be also sensitive to real that are occurring in a second object are (when the audience looks). Thus, magicians
motion54,55. Thus, implied motion might missed. such techniques are considered to strive to redirect the audience’s attention
activate similar circuits to those that are induce topdown attentional control (and away from the moment of the method and
active during the perception of real motion, are used by magicians to accomplish ‘active towards the moment of ‘magic’. Indeed, in
and this might result in perceptual illusions. misdirection’ (REFs 7,56) or by psychologists many magic tricks the secret action occurs
Another example of this might be when one to accomplish ‘endogenous attentional when the spectators think that the trick has
pretends to throw a stick for a dog during a capture’) because they modulate (increase not yet begun, or when they think that the
game of fetch. or decrease) neural activity in lowlevel trick is over. Many magicians use comedy
brain areas through feedback pathways from and laughter as a way to reduce focused
How do magicians misdirect the audience’s highlevel brain areas that are involved in attention at critical points in time. The
attentional spotlight? Magicians can cognitive functions64. One example of top magicians’ term ‘time misdirection’ refers
effectively control an object’s salience by down attentional modulation is provided by to the deliberate separation of the moment
manipulating the audience’s bottomup recent work by Chen and colleagues65, which of the method from the moment of the
and/or topdown attentional control shows that neural responses in the primary effect. Usually a delay is introduced between
mechanisms. Objects that are new, unusual, visual cortex, an early visualprocessing area, method (that is, cause) and effect, preventing
of high contrast or moving are salient, and are enhanced as a function of task difficulty the spectator from causally linking the two7.
the audience’s attention is more strongly during attentional tasks. Another example
drawn towards them. such object properties of topdown attentional control is when a Memory illusions and illusory correlations.
induce bottomup control of attention (and magician asks the audience to watch care Magic works in adverse circumstances: an
are used to accomplish ‘passive misdirection’ fully an object that is being manipulated in important part of the entertainment is that
in magic theory7,56 or ‘exogenous attentional one hand, while at the same time conducting spectators are naturally suspicious and will
capture’ in psychology) because the attention a secret action with the other hand. try to discover the method behind the trick.
is driven by increased activity in the ascend The principles that underlie attentional Thus, observers of a magic trick will often
ing sensory system. One way in which a capture and contrastgain control and adap try to reconstruct events to understand what
magician might control bottomup attention tation also apply to other sensory systems, happened. However, a successful magi
is by suddenly producing a flying dove. The for example the somatosensory system. cian will either have made it impossible to
spectators’ gaze and attention will focus on Pickpockets use techniques similar to those discover the method, or will seem to have
the dove’s flight, and this will give the magi that are used by magicians (for instance, ruled out all possible methods (including
cian a few unattended moments in which he sleightofhand manoeuvres) to manipulate the actual method) until magic is the only
or she can conduct a secret manoeuvre. the awareness and attention of their marks. apparent explanation7,68 (see supplementary
Another facet of bottomup attention that One way in which pickpockets manipulate information s1 (movie)). The magician
magicians exploit is the fact that if more than the somatosensory system by applying the can also influence the spectators’ recall of
one movement is visible, spectators will tend axiom ‘A big move covers a small move’ is the performance by using misdirection:
to follow the larger (that is, the more salient) as follows. To steal a watch directly from events that draw the spectators’ attention
motion7. Hence the magician’s axiom, ‘A big the wrist of a mark, the pickpocket might will be better remembered than less sali
move covers a small move.’ A neural process first squeeze the wrist while the watch is still ent events7,24,69. An apparently natural or
that might underlie this axiom is the low on66 (invoking contrastgain adaptation). spontaneous action, such as scratching one’s
level mechanism of contrastgain control (or This has two effects. First, it makes a high head, will not be memorable (although it
contrastgain adaptation)57. In contrastgain contrast somatosensory impression that might be critical to the execution of the
control, the perceived contrast of a stimulus adapts the touch receptors in the skin, trick). Unspoken assumptions and implied
is affected by the contrast of surrounding making them less sensitive to the subse information are also important to both the
stimuli (whereas in contrastgain adapta quent light touches that are required to perception of the magic trick and its sub
tion, the perceived contrast of a stimulus is unbuckle and remove the watch. second, sequent reconstruction7. J.r. has observed
affected by that of a preceding stimulus)58. the highcontrast impression leaves behind that spectators are more easily lulled into
A large or fastmoving stimulus might a somatosensory afterimage, giving rise to eagerly accepting suggestions and unspoken
therefore decrease the perceived salience of a the illusion that the watch is still on after it information than into accepting direct
small or more slowly moving stimulus that is has been removed. assertions70 (see supplementary information
presented either simultaneously (in Another way in which magicians can s2 (movie)). Thus, in the process of recon
contrastgain control) or subsequently alter an object’s salience is to split the audi struction, implication can be remembered
(in contrastgain adaptation). novel stimuli ence’s attention by introducing several con as direct proof. The magician can further
are known to produce stronger neural current actions24. If two actions start almost influence future recollection by describing
responses in the inferotemporal cortex (area simultaneously, the one that begins first will past events in a manner that will bias the
IT), the hippocampus, the prefrontal cortex usually attract more attention7,67. social cues, reconstruction process7. This is known in
and the lateral intraparietal area59–63; these such as the magician’s gaze (for instance, cognitive science as the ‘misinformation
effects are attributed to bottomup in the VanishingBall Illusion), their voice effect’ — that is, the tendency for mislead
attentional processes. and verbal communication and their body ing information presented after the event
The salience of an object can also be language (pointing, tension/relaxation), also to reduce one’s memory accuracy for the
increased by actively directing attention play an important part in manipulating the original event. This effect can even lead to
to it. For example, a magician might ask spectator’s attentional spotlight7. the creation of a ‘false memory’ for events
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that never took place69. The famous Indian Magicians can also make their audiences established, activity in the ventral tegmental
rope Trick legend might have partially incorrectly link cause and effect. We all infer area, which is linked to the evaluation of
resulted from the misinformation effect. cause and effect in everyday life. When A expected and realized reward, was cor
In the Indian rope Trick, a boy climbs a precedes B, we often conclude that A causes related with the maintenance of ‘conditional
magically suspended rope and disappears B. The skilled magician takes advantage of trust’ (REFs 79,80). ‘Unconditional trust’ was
at the top. The magician follows the boy up this inference by making sure that event A correlated with activity in the septal area,
the rope into the invisible area at the top (for example, pouring water on a ball) always which is linked to social attachment81–83.
and cuts him into pieces (evidenced by the precedes event B (in this case, the ball disap Future research will determine the role of
bloody body parts falling from the invisible pearing). However, A does not actually cause conditional versus unconditional trust in con
area down to the ground). The magician then B: the magician only makes it seem so74,75. fidence fraud schemes. neuroscientists can
descends the rope and magically reintegrates This type of illusion — seeing a correlation take advantage of the persuasion techniques
the boy with no harm done. In fact, the that is not there — is termed an ‘illusory cor that are used by magicians and pickpockets
Indian rope Trick has never been performed, relation’. Illusory correlations can arise from to identify the neural circuits that underlie
despite numerous witness accounts71–73. unequal weighting of information, from feelings of trust and mistrust.
Although the study of false memory and the participants’ expectancies (such as prior
misinformation effects has become a main beliefs or stereotypical knowledge) and/ Magic principles
stream topic in cognitive science over the past or from selective attention and encoding. Various principles of stage magic aim to
few decades, it is possible that the field would In this third possibility, illusory correla manipulate attention and awareness. These
have advanced faster if scientists had looked tions arise when some events capture more principles have been identified by magicians
at the magicians’ intuition of human memory attention or are more likely to be encoded and have been refined over the centuries
earlier. even today, despite the substantial in memory and remembered than other, to great effect. The time is now ripe to take
progress that scientists have already made in less salient, events76. Thus, the magician them into the laboratory and use them to
this area, the misinformation effect as used can effectively use misdirection techniques guide new and more powerful experimental
by magicians could be robustly reproduced to draw illusory correlations between two testing and careful quantification. This
in the laboratory to study the neural under unrelated events. Just as visual scientists use would elucidate the mechanistic pathways
pinnings of memory mechanisms and, in visual illusions to identify the neural mecha in the brain that allow magic tricks to work
particular, falsememory mechanisms. nisms of perception, neuroscientists could and would also generate novel and robust
use illusory correlations to identify the neu laboratory techniques for studying atten
ral mechanisms that underlie the cognitive tion and awareness. A number of magic
Glossary computations of cause and effect. In a recent principles were discussed during the Magic
study by Parris and colleagues77, participants of Consciousness symposium during the 11th
After-discharge
A sensory neuron’s response to the turning off of a underwent functional MrI (fMrI) while Annual Meeting of the Association for the
stimulus. watching films of magic tricks that involved scientific study of Consciousness (BOX 2);
apparent cause–effect violations. The brain they are reviewed below.
Blindsight activation that was induced by the watching
A neurological condition in which a patient with damage in
the primary visual cortex is unaware of visual events that
of these films was compared with the activa An action is a motion that has a purpose.
occur in the corresponding portion of the visual field, tion that occurred in a control condition in During the execution of a magic trick, it is
despite exhibiting good performance on visual tasks which participants watched video clips of necessary to use unnatural actions. Thus,
conducted in that region. events that did not involve apparent causal the magician needs to reduce the audience’s
violations. The results showed greater activa suspicion about such actions. One way to do
Change blindness
The failure to notice changes in an object or scene over a tion in inferior medial frontal areas during this is to justify unnatural actions so that
period of time. the viewing of magic tricks than during the they seem natural7. Teller74 refers to this
viewing of the control videos. principle with the aphorism, “An action is a
Inattentional blindness motion with a purpose.”
The failure to notice a salient object or visible feature in a
scene owing to misdirected attention or attention that is
The illusion of trust. Pickpockets rely heav In everyday life we categorize the
not engaged at a level sufficient to achieve awareness of ily on social misdirection. Gaze contact, motions made by others by interpreting
the object. body contact7 and invasion of the mark’s their intentions. If we see somebody
personal space24 are effective misdirection pushing their glasses higher on the bridge
Magic palming technique
techniques (see supplementary information of their nose, we assume that the glasses
The technique used by magicians to hide items in the palms
of their hands (which are turned away from the observer), s3 (movie)). Further, magicians and profes needed adjustment, and no further inter
so as to make it look like the hands are empty. sional pickpockets use established techniques pretation is made. A good magician makes
of persuasion to manipulate the trust of their use of such innocent actions to hide ulte
Microsaccades audiences/marks. some of these principles rior motions in a process called ‘informing
small, involuntary saccades that are produced when
subjects attempt to fixate their gaze on a visual target.
are also used by confidence artists in various the motion’. For instance, magicians with a
scams and frauds. Brainimaging studies of mute onstage persona, like Teller, can take
Saccade subjects playing online trustbuilding games advantage of the glassespushing action
A fast, jerky eye movement that transports the fovea from show that activation in the paracingulate to discreetly hide a small object in their
one visual target to another in a straight-line trajectory.
cortex is critical to building a trusting rela mouth (being mute, they have no lines to
Smooth pursuit movement tionship. This activation seems to be related garble). A less clever magician might
A type of eye movement in which the retinal fovea to inferring the partner’s intentions so as to do the same motion (moving the hand
smoothly tracks the position of a moving object. predict their behaviour78. Once trust was over the mouth) without informing it with
6 | ADVAnCe OnlIne PUBlICATIOn www.nature.com/reviews/neuroPersPectives
and colleagues, most observers caught the
Box 2 | The Magic of Consciousness symposium
method when the trick was shown a second
time35,36,40,88. similarly, most inattentional
blindness demonstrations are a onetime
only kind of effect. Observers are much
more likely to see the gorilla the second
time they watch the basketball video
described earlier33.
conclusions
Magic combines multiple principles of atten
tion, awareness, trust and perception to both
overtly and covertly misdirect the audience.
Whether they are used for performance art
or as a means to illicitly separate victims
from their money and valuables, the accom
plished performer uses robust and intuitive
manipulative devices that are of great inter
The Magic of Consciousness symposium took place during the 2007 meeting of the Association for est to neuroscientists pursuing the neural
Nature Reviews | Neuroscience underpinnings of cognition, memory, sensa
the Scientific Study of Consciousness (Las Vegas, Nevada, June 22nd–25th). In this symposium, the five
magicians authoring this paper (M.K., J.R., A.R., T. (the photos show T. demonstrating The Miser’s tion, social attachment, causal inference and
Dream at the symposium) and J.T.) shared their insights about how stage-magic techniques might awareness. Among these devices, we would
manipulate attention and awareness75,94. The audience consisted of cognitive neuroscientists and like to emphasize the use of misdirection as
consciousness researchers, and the symposium was geared towards establishing collaborations a means to generate cognitive illusions such
between magicians and scientists so that magic tricks could be replicated in the laboratory. See as inattentional blindness, change blindness,
Supplementary information S1–S6 (movies) for symposium footage that shows how attention is memory illusions and illusory correlations.
manipulated during magic tricks. The photographs of T. were taken by Jane Kalinowsky for The New
Magicians are able to obtain these effects
York Times94.
under conditions of high scrutiny show after
show. some of the crucial principles one
a purpose (adjusting one’s glasses). such a But the magician can covertly change the needs to take into account when designing a
motion will be subject to suspicion and method that underlies each apparent repeti robust trick are the understanding that every
scrutiny. In that case, even if the specta tion of the effect. Indeed, when a good magi motion should seem to have a purpose, that
tors have not seen exactly how the trick cian repeats an effect, the method is varied in the magician should not perform the same
works, they might feel that something is imperceptible ways and in an unpredictable exact trick twice, and that the most success
amiss. The skilled magician informs every rhythm. That way, each time observers ful tricks use apparent repetition to close
motion with a convincing intention (see suspect one method is being used, they find all the doors on every possible explanation
supplementary information s4 (movie)). their suspicion disproved by the subsequent of the trick except for ‘magic’ itself.
repetition74 (see supplementary information Cognitive neuroscience endeavors to
Apparent repetition, priming and ‘closing s4 (movie) and s5 (movie)). The magician reverseengineer the entire spectrum of
all the doors’. In everyday life, by repeatedly might even deliberately raise suspicion cognition by determining the neural cor
observing a process we are able to deduce about a possible method and then show that relates of the various cognitive processes that
its workings. Priming is a type of repetition suspicion to be unfounded7. In this way, the make up our lives. Magic techniques can
effect in which the presentation of a stimulus magician closes the door on every possible provide methods and insights that could help
that is similar to a target makes subsequent explanation for the trick68,73,86, until the only to explain what happens in the brain when
presentations of the target perceptually more remaining possibility is ‘magic’. This tactic a spectator thinks he knows what happened
salient84. Priming is used experimentally, and is referred to as Tamariz’s Theory of False on stage73. The possibilities of using magic as
by the magician, to affect the subject’s sen solutions (see supplementary information s1 a source of cognitive illusions to help isolate
sitivity to a later presentation of a particular (movie)). The use of apparent repetition has the neural circuits that underlie specific cog
stimulus. Moreover, repetition can be used to the added benefit of confusing the spectators’ nitive functions are endless. For example, the
induce sensory illusions, as in the Vanishing reconstruction process. Further, the specific magicians authoring this article emphasize
Ball Illusion described earlier. spectators are weaknesses of each method will cancel each the use of humour as a critical aid to the
more likely to perceive the illusory ball van other out7. successful implementation of many tricks.
ishing in midflight if an actual ball has been Their intuition is that when the audience is
tossed several times first, so that they are Never do the same trick twice. The corollary laughing it is as if time stops and the atten
primed to know what an actual tossed ball of the closing all the doors principle is that if tional spotlight is put on hold. That is, the
looks like85. Thus, priming and repetition can the magician performs the same trick twice magician can do virtually anything when the
be helpful in inducing some illusory effects. for the same audience, there is an increased audience is laughing, and nobody will notice.
Magicians also use repetition to hide the chance that the audience will identify the recording neural activity (by fMrI, electro
method behind the trick: when observers see method that is being used and figure out encephalogram, magnetoencephalography,
an effect repeated, they naturally assume that the trick87 (see supplementary information et cetera) in someone who is watching magic
each repetition is done by the same method. s5 (movie)). In several studies by Kuhn tricks that are accompanied by humour
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