//SciPhi On Magic

SciPhi On Magic

Have you ever watched a magic trick and thought ‘how did he do that?’ From the simplest card trick right up to the most complex stage show, magic requires us to suspend belief and accept that the magician can play with the laws of nature, even though we know that we are being fooled. Knowing how a trick is done can often diminish it, of course, and yet learning how all magic tricks work is the goal of a growing number of psychologists. But their aim is not to diminish magic, or to spoil it for the rest of us, but rather to increase our understanding of the mind.

At the forefront of this research into magic is the psychologist Gustav Kuhn, who also happens to be a keen magician and so has developed a special interest in how the knowledge and experience of magicians can be used to further our understanding of how the mind works. Together with fellow psychologists Alym Amlani and Ronald Rensink, Kuhn has recently argued that by ignoring magic, cognitive science is neglecting an important source of insight into the human mind.

Over the centuries magicians have learned how to perform acts that are perceived as defying the laws of physics and logic, leaving audiences baffled and amazed. Yet there is nothing supernatural about these effects. Kuhn and his colleagues argue that the links between magic and human cognition have been largely ignored by modern psychology but that there is great scientific potential in studying the ways that people can be made to believe in such apparently impossible events. The time has come, they say, to examine these phenomena more closely and to connect them to current theories and methodologies for exploring the human mind. In particular, they argue that the effects produced by magicians can provide scientists with valuable tools to investigate human perception and cognition.

The basic rationale behind their work is that the history of science has shown that theories often stem from knowledge obtained from practical applications; for example, the science of thermodynamics arose from the development of steam engines. They believe that a similar situation exists with magic. Over the centuries, magicians have accumulated considerable knowledge about inducing striking effects in human observers. They believe that this knowledge can be systematised and used as a source of insight into mechanisms central to human perception and cognition. In addition, these effects also suggest new methodological techniques to investigate the relevant processes.

They illustrate their point by examining three general methods used by magicians: misdirection, illusion, and forcing.

There is a common belief that magicians hide their methods by relying on speed. But the success of a magic effect usually relies on misdirection, on the diversion of attention away from the method, so that the audience does not notice how it was produced. This reliance on misdirection to achieve an illusion is closely related to recent findings in vision science that only a small part of the information that enters our eyes (the part that is attended) enters our conscious awareness. Magicians have known this for centuries, and have accumulated considerable practical knowledge about how to control the relevant mechanisms. They have proposed a framework that distinguishes between physical misdirection, based on the physical properties of the stimulus, and psychological misdirection, based on control of higher-level expectations.

Physical misdirection refers to the control of attention via stimulus properties. The magician’s goal is to create areas of high interest that capture the spectator’s attention, while the method is covertly carried out in an area of low interest. Psychological misdirection controls spectators’ attention by manipulating their expectations. The magician’s aim is to reduce suspicion that a deceptive method has been used. Related to this is a key rule in magic which states that tricks should never be repeated, and it has been shown that both repetition and prior knowledge about what the spectator will see increases the likelihood that the observer will detect the method.

Regarding the second general method used by magicians, illusion, work in vision science has shown that much of vision is essentially a form of intelligent hallucination. To perceive depth, for example, the visual system must recover the third dimension from the two-dimensional image available on the retina. However, since multiple solutions are usually possible for a given image, the result must be obtained by applying assumptions of some kind. This approach, however, can sometimes lead to errors, which take the form of illusions. Two types of illusions are typically employed by magicians: optical, which involve physical factors, and cognitive, which involve psychological ones.

These illusions are thought to work because the finite speed of neural transmission causes a delay of approximately 100 ms between stimulus arrival and conscious awareness. One way of compensating for this is to predict the outcome of an event before it has been completely processed. This strategy is particularly useful in situations that require rapid response, such as when an organism is hunting or fleeing. But such predictions, useful though they undoubtedly are, can also make us vulnerable to deception. Effects such as the vanishing coin illusion (in which the spectator perceives the magician transferring a coin from one hand to the other, and the coin then vanishing) are experienced whenever the available evidence is consistent with the prediction made by the spectator. Kuhn argues that effects of this kind may serve as useful starting points for the empirical investigation of the subjective aspect of perception.

The third general method used by magicians is exemplified by the classic “pick a card, any card” trick, in which a subject chooses a card at random (or so they think) from the deck. The trick relies on the fact that the subject really feels as if their choice is free, whereas in reality it is highly controlled, thus enabling the magician to know what it is “by magic”. This process is known as forcing and according to Kuhn has interesting connections to recent work showing that observers often confabulate about the reasons for their choices; that is, they fill in gaps in their memory with fabrications that they believe to be facts.

Magicians have long known of this effect and typically use two different types of force. The physical force influences a spectator’s selection when asked to physically select an object, such as picking a card. The mental force influences the choice of a spectator who is instructed to think of an item. In both cases, the key is to create appropriate assumptions, and to avoid having the spectator become aware of the fact that his/her choice was controlled.

Kuhn and his colleagues admit that few magic tricks have been explored scientifically and few of the mechanisms involved are well understood, but argue that those few that have been studied indicate that magic and psychology have much to learn from each other:

“Ideally, this could be done via a ‘science of magic’,” they write, “which would explain all known magic effects in terms of known perceptual and cognitive mechanisms. Such a science might be able to reduce all known magic effects to a set of basic operations (such as physical and psychological misdirection) which are relatively well understood; any effects not reducible this way would indicate the existence of an unknown perceptual or cognitive mechanism.”

They also believe that a science of magic could have important practical applications. For example, human-computer interactions might be made easier if the users’ attention is guided so that they are more likely to carry out the right procedure. And they point out that many of the techniques used in advertising and political propaganda resemble the methods of the magician. Since there will always be motives for manipulating our choice, an important challenge for the future will be to understand these techniques sufficiently to ensure our freedom of choice. Now that would be worthy of an “Abracadabra”.

Suggested Reading
“Towards a Science of Magic,” Gustav Kuhn, Alym Amlani and Ronald Rensink, Trends in Cognitive Sciences, Vol 12 (Sept 2008).