1. Give a bried history of the scientific understanding of stage magic.
2. What is neuromagic?
3. What can neuroscientists learn about the neuroscience of magical phenomena performed by stage magicians?
4. Describe the different kinds of misdirection, illusions, and forcing.
5. What is an ongoing issue in the understanding of misdirection?
6. Explain some criticisms of neuromagic.
7. List future directions for the field of neuromagic.
Alfred Binet (1894): La Psychologie de la Prestidigitation
- recruited five stage _________
- filmed their performances, and analyzed them frame-by-frame
- concluded that “The illusion of each trick is not merely the result of one single cause, but of many, so insignificant that to perceive them would be quite as difficult as to count with the naked eye the grains of sand on the seashore.” (p.558)
Joseph Jastrow (1897):
- did experiments with world-famous _________
- published articles on the psychology of magic: The Psychology of Deception (1888), and Psychological Notes on Sleight-of-Hand Experts (1896)
- stated there was “much to interest the student of science in the elaborate performances of the prestidigitateur and the illusionist” (1897, p.851)
Norman Triplett (1900): The Psychology of Conjuring Deceptions
- categorized dozens of conjuring tricks into categories like “optical illusions,” “tricks involving scientific principles,” “tricks involving unusual ability, superior information, assistance of confederates, etc.,” and “tricks depending on a large use of fixed mental habits in the audience”
- experimental study: performed the vanishing ball illusion for schoolchildren; the majority of children “[saw] the ball go up and _________” (p.493)
Recent interest in the scientific study of stage magic has been increasing exponentially (Tompkins, 2018):
- 12 experimental scientific papers published on performance magic from 1887-1999
- over 110 published since 2000
Martinez-Conde & Macknik (2007): The Magic of Consciousness Symposium
- held in in Las Vegas on June 24, 2007, hosted by the Association for the Scientific Study of Consciousness
- demonstrated the intuitive ________ of magicians
- magic tricks may help uncover new ways of investigating attention and awareness
Kuhn, Amlani, & Rensink (2008): Towards a science of magic
- argued that cognitive science should not neglect effects created by magicians, which are “an important source of insight into the human mind”
- called for a general psychological ______ of magic
- a “science of magic” can direct new research into human perception and cognition
- this can be done by studying the processes stage magicians use to control attention (misdirection), distort perception (illusions), and influence choice (forcing)
Macknik et al. (2008): Turning tricks into research
- co-authors included professional stage magicians Mac King, James (The Amazing) Randi, Apollo Robbins, Teller, and Johnny Thompson (The Great Tomsoni)
- argued for a _______________ approach to understanding magic: “neuromagic” (Martinez-Conde & Macknik, 2008)
- neuromagic is the scientific study of the experience and performance of stage magic:
• to explain the underlying psychological principles of perception, attention, and cognition
• to gain a greater understanding of the neural __________ of those principles
• and to apply those principles to the development of new stage illusions
- in other words, science can learn from magic, and magic can learn from science
Otero-Millan et al. (2011): reciprocal relationship between magicians and scientists
- observers watched videos of Apollo Robbins performing the French Drop coin vanish trick
- coin is apparently taken by right hand, but is actually ________ in the left
- eye tracker used to record eye fixation locations
- two conditions: right hand traveling in straight motion path, or curved motion path
- results: observers’ fixation jumped back to the left hand in the straight motion condition, but remained on right hand more often in the curved motion condition
• straight motion path caused (fast) ________ eye movements
• curved motion path produced slowed smooth _______ eye movements--and prevented observers from looking back at the hand that retained the coin
- magicians manipulate not only the audience’s gaze position during a sleight, but also subsequent gaze location once the sleight is complete
- the hand is not quicker than the eye
- illustrates magicians’ intuitive understanding of visual perception, and how it can be informed by science
(Kuhn, Amlani, & Rensink, 2008; Martinez-Conde & Macknik, 2008)
• misdirection: drawing the audience’s attention away from the “method” (the secret behind the “effect”) and towards the effect (what the spectator perceives)
- subtypes:
▸ _____: observer’s gaze is directed away from the process
▸ ______: observer’s attention is directed away from the process (e.g., change blindness and inattentional blindness--see below)
- underlying processes:
▸ ________ misdirection: directs attention via properties of a stimulus (bottom-up/exogenous control), such as movement, contrast, and novelty, and magician’s eye gaze or body posture
e.g., disappearing objects magic trick depends on magician’s eye gaze (Kuhn & Tatler, 2005)
▸ _____________ misdirection: directs attention via beliefs and expectations (top-down/endogenous control), such as secret props, suspense, and false solutions
e.g., in the French Drop, the magician’s actions must appear natural to avoid arousing suspicion
• illusions
- _______ illusion: false perception created by manipulation of the physical properties of light via intricate combinations of mirrors and perspective
e.g., Pepper’s ghost: an illusory transparent object is seen
- created by projecting an image onto a pane of glass
- ______ illusion: subjective visual percept of a stimulus that does not match objective reality
e.g., spoon bending
e.g., retention of vision vanish: coin is perceived to be placed in one hand--but it remains in the other
- removed object will still be perceived for ~100 ms
- due to neural after-discharge
e.g., Tri-Zonal Space Warper (Jerry Andrus, 1977): adapting to a rotating stimulus subsequently makes stationary stimuli seem to warp and move
- application of motion ___________
- due to adaptation of neurons sensitive to motion in a particular direction
- _________ illusions: false perception created by manipulating high-level processes like attention, memory, and causal inference (drawing conclusions about apparent cause and effect)
▸ ______ blindness: when a visual stimulus undergoes a change, observers often fail to notice the change
e.g., Richard Wiseman’s (2007) Colour Changing Card Trick
- requires attention to stimuli and memory comparison
- often occurs when stimuli are visually interrupted (Rensink et al., 2000)
Kuhn et al. (2016):
- observers watched a magician perform the Princess card trick (selected card “disappears”)
- but the backs of the cards also changed from blue to red
- in the middle of the trick, magician made eye contact and asked observer a question (______ misdirection)
- observers’ eyes were tracked, and were asked at the end if they detected the colour change
- conditions: naïve (no instructions) vs. misdirection warning (observers told to keep their eyes on the cards)
- change noticed by only 30% of observers
- change detection performance was not affected by the warning, or by where observers looked (overt attention)
- warning reduced time spent looking at the face, but did not eliminate it
- implication: asking a question misdirects attention towards the magician’s face and prevents people from detecting the trick
▸ _____________ blindness: when observers are focused on an object or event, they often fail to notice other salient or distinctive stimuli
e.g., Barnhart & Goldinger (2014):
- observers showed video of a coin being placed under a napkin
- in a critical trial, a string visibly pulls the coin from under one napkin to the other
- preview condition: three control trials (coin does not move) presented before critical trial (coin moves)
- no-preview condition: critical trial presented once
- observers asked where the coin was now located
- eye tracker used to record eye fixation locations
- inattentional blindness results: preview condition: 18% missed the moving coin; no-preview condition: 55%
- supports perceptual ____ theory: preview condition left observers with more attention to detect the moving coin
▸ ______ blindness: when observers choose an item, but are later presented with a different item that is supposedly their chosen item, they often fail to notice the discrepancy
e.g., Hall et al. (2010):
- invited shoppers to try two different jams and choose which one they preferred (e.g., cinnamon-apple or grapefruit)
- secretly switched the jams, using double-sided containers
- immediately after choosing, observers were asked to sample their favourite and explain their choice
- only 33.3% of observers detected the switch
- most confabulated (generated fabricated reasons) to justify the outcome, which was the opposite of their actual choice
▸ illusory ___________: believing that there is a relationship between two events, when none actually exists
e.g., Parris et al. (2009):
- observers watched videos while in fMRI
- magic condition: videos of magic tricks that violated cause-effect relationships (e.g., disappearing coin, £5 note is folded and unfolded to reveal a £10 note)
- surprise condition: videos of unexpected events (e.g., a third hand steals the coin, £5 note is torn in half)
- causal control condition: similar videos with no tricks or surprises (e.g., coin does not disappear, £5 note is folded and unfolded)
- surprise condition produced greater activity in anterior cingulate cortex (ACC), associated with detecting conflict/allocating attention
- magic condition produced greater activity in areas of dorsolateral prefrontal cortex (DLPFC) in the left hemisphere
- conclusion: DLPFC involved in detecting violations of _________
• forcing: an apparently free will choice is controlled by the magician
- ________ force: selection of a physical object is controlled by physical manipulation
e.g., pulling one card from a deck--which is made up of 52 aces of spades
- ______ force: choice of a piece of information is controlled by its presentation
e.g., choosing one card from a deck--which is manipulated to be displayed longer than any other card
Olson et al. (2016):
- professional magician approached people in Vancouver
- performed visual riffle force: in riffling through a deck of cards, one was manipulated to be shown longer
- observers were asked to choose any card
- results: 98% chose forced card; 91% were unaware of the manipulation
- for unaware observers, the most important predictive factor was the personality trait of _______________: the threshold for stimuli to enter conscious awareness
- 16% of observers confabulated reasons for their choice
- magic may reveal the nature of free will and choice
Issue: What cues affect misdirection? Are ______ cues relevant?
Kuhn & Land (2006):
- observers watched the _________ ball illusion
- conditions:
• pro-social cues: magician moved head and eyes up to follow an imaginary ball
• anti-social cues: magician looked at hand concealing the ball
- gaze recorded using an eye tracker
- results:
• pro-social cues: 63% perceived the ball leave his hand, move upwards, and disappear
• anti-social cues: only 32% perceived the illusion
• eye tracker showed observers glanced at magician’s face before looking at the ball
- conclusions:
• magicians can use _____ _________ cues (e.g., their own gaze) to strengthen perception of magic
• joint attention: multiple people paying attention to an object, via verbal cues, eye-gaze, gestures, or other non-verbal cues
Rieiro, Martinez-Conde, & Macknik (2013):
- observers watched videos of Teller performing the “cups and balls” magic trick, in which balls appear and disappear inside three upside-down cups
- observers pressed one button when a ball was placed, and another when a ball was removed
- gaze recorded using an eye tracker
- conditions:
• standard trick, ball dropped on floor, ball placed on table, ball stuck to cup
• half the trials used opaque cups, the other half used transparent cups
• half the trials showed magician’s face, the other half occluded his face
- results:
• detection performance worse in table and stuck conditions (contrary to magician’s intuition)
• detection of loading the third cup was at chance level with opaque cups, but above chance with transparent cups (about 75%)
• performance improved with increasing numbers of trials
• performance equivalent in face visible and face occluded conditions
- conclusions:
• suggests ways magicians can enhance this trick
• magician’s gaze (______ misdirection) had no effect
• _________ problems (e.g., not every trick works every time, requires trained performer with specialized abilities, etc.)
• Thomas et al. (2015):
- in 10 years, no ___ cognitive phenomena have been discovered by studying magic
- there are many aspects of magic that have yet to be explored (e.g., perceptual anticipation, patter, expertise at pantomime)
• Lamont, Henderson, & Smith (2010); Lamont (2015)
- a “science of magic” is misguided
- distractions used experimentally are different from misdirection in magic
e.g., inattentional blindness paradigms use explicit distractor task to divert attention (count the number of basketball passes), whereas misdirection paradigms are implicit (looking at one of the magician’s hands but not the other)
- there is too much variability among magic tricks, and they overlap in many ways
e.g., some tricks rely on misdirection, illusion, and forcing
- there is too little structure for a given trick, which can be performed many different ways
e.g., in The Materializing Card trick, a freely chosen card may be forced a number of different ways, then reappears inside a lemon, an orange, the observer’s pocket, etc.
- due to the ___________ in methods and effect, it is impossible to create a taxonomy of magic
• resolve the debate about the role of social cues in misdirection, and determine the cognitive and neural mechanisms involved (Kuhn & Martinez, 2012)
• focus not on surface differences that exist in the method and effects of magic tricks, but on the underlying psychological principles, in order to gain a deeper _____________ (Rensink & Kuhn, 2015)
• further establish the ecological validity of neuromagic research: to what extent does it accurately reflect real-world, everyday experiences?
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