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About “Neuro-Magic” is the term coined by Susana Martinez-Conde and Stephen Macknik to describe the application of neuroscientific techniques to study magic. The underlying premise of “Neuro-magic” is that by gaining an insight into how magic tricks operate via the perspective of the audience, it is possible to uncover the neurological foundation of consciousness.

Applying Neuroscience to Magic
Visual Illusions Visual illusions are an unequivocal illustration that our idiosyncratic, subjective perception of the environment around us does not always correspond to reality. This makes illusions an indispensable mechanism for explaining neural circuitry and everyday confabulations that our brains make when constructing reality. In order to understand how visual illusions operate it is important to have a basic knowledge of the human visual system itself. The primary layer of the human visual system is comprised of photoreceptors. These photoreceptors act by converting light rays into electrochemical neural messages in order to help the brain to identify contrast. Magicians have astutely created illusions that capitalise on our innate ability to detect contrast; for example, Black Art. Visual information originating in the retina is transmitted to the optic nerve which simultaneously transports electrochemical signals to the primary visual cortex, via the thalamus. Furthermore, as illustrated by the Nobel Prize award winning work of Hubel and Wiesel, the primary visual cortex accommodates neurons which selectively fire in response to line orientation and various visual characteristics. Throughout this process, the visual system works on inference alone, therefore, it simply creates the most tenable interpretation based on the available cues This explains how magicians can create card tricks, make you believe they are bending spoons before your eyes, and even call upon specific components of the visual system to cause momentary blindness.

A pertinent example of how knowledge of illusions has advanced the field of neuropsychology can be found in kinetic illusions. These illusions are defined as when a static image creates the powerful illusion of motion. Examples include Enigma and the Snake and Spiral Illusion. In the endeavour to find an explanation for how kinetic illusions operate Troncoso, Macknik, Otero-Millan and Martinez-Conde conducted an experiment. Within the experiment, participant’s eye movements were recorded. Concurrently, they were asked to view the static image and report when they perceived the illusory motion to either have got faster or slower. Before participants perceived the motion to have sped up, their number of microsaccades - small eye movements that take place whilst an individual fixates on an image – heightened. This correlation between microsaccades and illusory motion perception led to the conclusion that kinetic illusions begin on an ocular rather than cerebral level. Another example, this time from the field of Arts, is the elusive smile of The Mona Lisa that seems only to exist when you fixate away from her mouth. Livingstone argued that this illusion occurs because central and peripheral vision creates two distinct perceptions of the world. On one hand, the fovea: central vision is attuned to perceiving detail, whereas peripheral vision is more attuned to shadows and motion. When the fovea is fixated elsewhere on her face, the mouth is integrated into our peripheral vision. Our peripheral vision therefore perceives the shadowing upon the face which embellishes the curvature of the smile.

Attention and Misdirection "Everyone knows what attention is. It is the taking possession by the mind in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought...It implies withdrawal from some things in order to deal effectively with others, and is a condition which has a real opposite in the confused, dazed, scatter-brained state." This quote by William James highlights how the human attentional system works like a spotlight. This creates a bias because when actively focusing on one thing we have a tendency to repress the surrounding environmental cues. This means that if our attention is wrongly focused, it is possible to miss important information. One empirical example of this attentional bias can be seen in the work of Simons and Chabris. In the experiment, participants were asked to watch a short video of people playing basketball and were asked to count how many passes were made between the team members. During the video, a man, who was dressed up in a gorilla suit, walked onto the centre of the basketball court but largely went unnoticed by the participants because their attention was focused elsewhere, see Change Blindness. To further explore these findings, Memmert used an eye tracking device to demonstrate that participants often did not register the existence of the man in the gorilla suit even when their eyes were focusing directly on him. This contradicted neuroscientific understanding at the time which assumed the basketball match acted as an overt form of misdirection, encouraging the participant’s eye focus away from the gorilla. However, Memmert’s findings can be used to argue that change blindness works on the principle of covert misdirection. Instead, the gorilla seemed invisible even when participants were looking straight at him because the game of basketball was acting as a distraction, drawing attention away from the other environmental cues. These findings can be used to explore how magicians use misdirection techniques to draw their audience’s attention away from a significant part of a magic trick. Similarly, these findings shed some light on how pick pockets can capitalise on human attentional biases and steal personal objects from individual’s right before their eyes.

Memory Scientists, and magicians alike, are all too knowing about the fallibility of human memory. The brain has a tendency to confabulate, even to the extent of creating false memories. This has been famously explored by Loftus and Pickrell who demonstrated how some psychiatrists and medical professionals instilled supposed repressed memories within their patients during therapy. This is an extreme example and for the most part, at least, false memory acquisition is prosaic and reasonably devoid of danger. When our brains are consolidating a new memory, they actually encrypt scattered constellations of significant junctures. When later retrieving a memory, the brain uses these junctures as a framework to reconstruct the experience. Some of these recollections can be accurate but equally a lot of these recollection can be inaccurate and full of confabulation. Nader emphasises this point in his research regarding memories relating to the attack on the Twin Towers in America. An astounding seventy three percent of participants recalled watching live footage of when the initial plane collided with the World Trade Centre building, however, this footage was not broadcasted until the day after the attacks

A notable example of a magic trick involving planting false memories can be found in the twisting arm illusion. This illusion involves the magician indulging in the impossible feat of twisting his arm around three hundred and sixty degrees. The magician uses his coat sleeve as a prop to hide the truth of the actions. After the first rotation, an audience member is invited on stage to try and repeat the trick. During the spectator’s attempt, the magician removes his arm from the table and resets it back in the same position. The audience’s attention is captured by the spectators attempt so they often do no recall the magician removing his arm from the table and instead create the false memory that the magician rotated his arm around twice. Capitalising on the fallibility of memory and manipulating how the audience proceeds to reconstruct the event after it has happened is the basis for a lasting and powerful magic trick.

References

DeLint, P. J., Berendschot, T. T., van de Kraats, J., & van Norren, D. (2000). Slow optical changes in human photoreceptors induced by light. Investigative Ophthalmology & Visual Science, 41(1), 282-289.

Hubel, D.H., & Wiesel, T. N. (1963). Effects of visual deprivation on morphology and physiology of	cells in the cat’s lateral geniculate body. Journal of Neurophysiology, 26, 978-993.

James, W. (1890). The Principles of Psychology. New York: Dover Publications

Lee, T. S., Mumford, D., Romero, R., & Lamme, V. A. (1998). The role of the primary visual cortex in higher level vision. Vision Research, 38(15), 2429-2454.

Livingstone, M. (2000). Is it warm? Is it real? Or just low spatial frequency? Science, 290, 1299.

Loftus, E. F., & Pickrell, J.E. (1995). The formation of false memories. Psychiatric Annals, 25(12), 720- 725

Macknik, S., & Martinez-Conde, S.L. (2008). Sleights of Mind: What the Neuroscience of	Magic Reveals About Our Brains. London: Profile Books.

Martinez-Conde, S.L. (2013). Illusion of the week: Black art in dance. Retrieved from:	http://blogs.scientificamerican.com/illusion-chasers/2013/08/29/black-art/

Martinez-Conde, S.L., & Macknik, S. (2008). Magic and the brain. Scientific American, 299, 72-79. Memmert, D. (2006). The effects of eye movements, age, and expertise on inattentional blindness. Consciousness and cognition, 15(3), 620-627.

Nader. K. (2003). Memory traces unbound. Trends in Neurosciences, 26(2), 65-72. Scientific American. (2013).

Simons, D. J., & Chabris, C.F. (1999). Gorillas in our midst: sustained inattentional blindness. Perception, 28, 1059-1074.

Troncoso, X. G., Macknik, S. L., Otero-Millan, J., & Martinez-Conde, S. (2008). Microsaccades drive illusory motion in the Enigma illusion. Proceedings of the National Academy of Sciences, 105(41), 16033-16038.